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December 26, 2019

Mechanics & Properties of Matter - Part 2

Magme Guru

MECHANICS & PROPERTIES OF MATTER - PART 2

CENTRIPETAL FORCE
Activity :
•    Swing a stone tied to a string and observe that the stone follows a circular path.
•    Let the string slip through your fingers and observe that the stone no longer follows a circular path but flies off in the direction of the instantaneous velocity.
•    This direction is tangential to the circular path. From this activity we understand that a force acting on the stone pulls it towards the centre of the circle.
•    This force is called the centripetal force. Centripetal force is the force needed to make an object travel in the circular path.
•    The centripetal force causes an acceleration towards the centre of the circle and this acceleration is called the centripetal acceleration.
•    The centripetal acceleration (ac) of an object in uniform circular motion is given by 

Centripetal force finds many practical applications :
•    In washing machine’s spin cycle, water is separated from the clothes. The tub of the washer rotates rapidly. The force exerted on the water present in the clothes is not much enough to make the water travel in a circle with the clothes. The water flies off, leaving the clothes less wet due to lack of centripetal force.
•    The less desirable case of lack of centripetal force is when the rear wheel of an automobile spins in mud. The adhesion of the mud to the wheel which is the centripetal force in this case is not enough to hold the mud on the tyre. So it comes off tangentially to the tyre’s circular motion.
•    Gravitational force between a satellite and the earth acts as a centripetal force, keeping the satellite in orbit.

CENTRIFUGAL FORCE :
•    We feel a force pushing us outward or away from the centre of curvature when we travel in a fast moving car rounding a sharp curve or in a rotating ride in an amusement park.
•    This force is known as centrifugal force. It acts in the opposite direction to that of centripetal force. The centrifugal force is also given by F =
•    When earth rotates about its own axis, the velocity of bodies near the equator is more than that at the poles.
•    On earth the centrifugal force is minimum at the poles and maximum at the equator. This is the reason why the poles of the earth are found to be nearly flat and the diameters of earth along the equator and poles are different by 48 km.
•    The centripetal force required for a car or a bicycle to go round a circular curve depends on its speed and the radius of curvature of the curve.

APPLICATIONS OF CENTRIFUGAL FORCE
•    The principle of centrifugal force is applied to the machines.
•    They are used to separate materials of different weights or densities by spinning action.
•    The liquid is rotated in a cylindrical vessel at a high speed with the help of an electric motor.
•    The heavier particles move away from the axis of rotation and lighter particles move nearer to the axis of rotation.
•    The spinning drum in a washing machine to separate water from clothes is a centrifuge.
•    Centrifuges are used in separating blood cells from plasma and cream from milk in dairy separators.
•    Ultra centrifuges with speeds of the order of 5 x 105 rpm are used to concentrate viruses in solution.
•    The holder of a centrifuge container is pivoted, so that the container will be in the horizontal position, when the centrifuge spins rapidly.
•    The heavier materials migrate towards the outer end of the container. For example when blood samples are centrifuged, the red cells reach the bottom and lighter white cells go to the top of the tube.
•    Sugar crystals are separated from molasses with the help of a centrifuge. Honey is also separated from bees wax with the help of a centrifuge.

WATT GOVERNOR :
•    Makes use of the centrifugal force for regulating the speed of an engine or machine. It consists of two heavy balls B1 and B2 joined to the ends of the rods R1 and R2 hinged at H, the end of the spindle S.
•    These rods are connected through the link rods L1 and L2 to a sleave m which can slide upand down on the spindle.
•    As the speed of the engine increases, the speed of rotation of the spindle also increases and consquently the centrifugal force on the balls B1 and B2 increases. Now the balls and the sleave move up due to the increase in speed of rotation of the balls.
•    This partially closes a valve which controls the entry of steam to the engine and the speed of the engine is checked.
•    Thus the speed of the engine is regulated by regulating the supply of steam.
•    In circus there is an event known as the cage of death. In this event, a motor cyclist drives a motor cycle at a high speed on the inner walls of a spherical cage of iron. But he does not fall off the motor cycle even when he is upside down.
•    The centrifugal force keeps the motor cyclist glued to his seat while driving his motor cycle inside the cage.
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December 26, 2019

Mechanics & Properties of Matter - Part 1

Magme Guru

MECHANICS & PROPERTIES OF MATTER - PART 1

The branch of Physics dealing with the behavior of matter under the action of forces is called Dynamics and Statics are the two branches of mechanics.

•    The mathematical and physical study of the behavior of bodies under the action of forces that produce changes of motion in them is known as dynamics.
•    Statics deals with the cases where no motion is produced in the bodies under the action of forces.
•    Objects have transnational motion, rotational motion and vibrational motion.
•    The motion of wheels, blades of fan, planets around sun and electrons around the nucleus of atoms are some examples of rotational motion.
•    Elasticity, surface tension and viscosity are a few important physical properties of matter.
•    These properties can be explained on the basis of forces between molecules of matter.
•    A thorough knowledge of properties of matter is essential in identifying different materials available with us.
•    This is useful in choosing proper materials for different applications.
•    This study is made use in the branch of physics called Properties of matter.
•    The basic concepts of Projectile motion, circular motion, gravitation,
•    planetary motion, surface tension, viscosity,
•    Bernoulli’s theorem and their applications.

MOTION OF FREELY FALLING BODIES AND PROJECTILE MOTION

FREELY FALLING BODIES
•    When an object falls towards the earth under gravity in the absence of air resistance, it is called a freely falling body.
•    All objects in free fall near the earth have the same acceleration called the acceleration due to gravity (g).
•    The gravitational force acting on an object of mass ( m) near the earth is its weight W = mg.
•    The acceleration of an object in free fall is independent of its mass. As air resistance normally acts on a falling body and opposes its motion, the object falls at a slower rate than in free fall.
•    Coin and feather experiment : Drop a coin and a feather simultaneously in a tube. Evacuate air from the tube and repeat the same dropping.
•    Observe that in the first case the coin which is heavier than the feather reaches the bottom of the tube more rapidly while the feather flutters down slowly.
•    But in the second case the coin and the feather to fall together.
•    From this experiment we understand that air resistance affects the motion of a falling
•    body. The air resistance on a falling body depends on its shape, size and speed.

Examples
•    A skydiver with an unopened parachute falls quite rapidly and when the chute opens due to the shape and size of the body the air resistance increases and the descent is slowed.
•    This is how the skydiving gives pleasure.
•    Automobiles are now streamlined in shape to reduce air resistance and improve fuel consumption.
•    When a body falls, it accelerates due to gravity and the retarding force of air resistance increases with speed. This continues till the force of air resistance equals the weight of the object. Now the object no longer accelerates but falls with a constant speed called the terminal velocity. The terminal velocity is about 200 km/hr for a skydiver with an unopened parachute.
•    While falling the skydivers use a “spread-eagle” position to increase the air resistance and prolong the time of fall. When the parachute is opened, the fall is slowed by the additional resistive force.

PROJECTILE MOTION
•    Any object which follows a path determined by the gravitational force and air resistance
•    when an initial velocity is given, is called a projectile.
•    A bullet shot from a rifle, a rocket after its fuel is exhausted, a javelin thrown by an
•    athlete and a thrown cricket ball are examples of projectile.
•    The path followed by a projectile is called its trajectory.

VERTICAL PROJECTION
•    We often throw or toss things directly upward and this is a vertical projection. The initial velocity of the object is upward but the acceleration due to gravity is downward.
•    Hence a vertically projected object at its maximum height stops instantaneously and changes its direction.
•    Now it becomes a dropped object in free fall.

MAXIMUM HEIGHT ATTAINED (h)
Let a body be projected vertically upwards with an initial velocity u. As it moves upwards its acceleration is taken as – g.

As the body goes up its velocity decreases and finally becomes zero ( v = 0) when it reaches maximum height.

The maximum height attained by a body is directly proportional to the square of its initial velocity u.
TIME OF ASCENT (t1)
•    The time taken by a body thrown up to reach maximum height is called its time of ascent.
•    Let t1 be the time of ascent. At the maximum height its velocity v = 0.

TIME OF DESCENT (t2)
•    After reaching the maximum height, the body begins to travel downwards like a freely falling body.
•    The time taken by a freely falling body to reach the ground is called the time of descent (t2). In this case u = 0 and g is positive.
•    It is an interesting fact that the time of ascent is equal to the time of descent in the case of bodies moving under gravity.

TIME OF FLIGHT
•    The time of flight is the time taken by a body to remain in air and is given by the sum of the time of ascent (t1) and the time of descent ( t2).

VELOCITY ON REACHING THE GROUND
•    When a body is dropped from a height h its initial velocity u is zero. Let the final velocity on reaching the ground be v.
•    From equations (8) and (9) we conclude that the velocity of the body falling from a height h on reaching the ground is equal to the velocity with which it is projected vertically upwards to reach the same height h.
•    Hence the upward velocity at any point in its flight is the same as its downward velocity at that point.
•    The value of g at a place can be determined by noting the time taken ( t) to cover a vertical height (h) in free fall

CIRCULAR MOTION :
•    Relation between Linear velocity and angular velocity
•    When a particle moves in a circle with a constant speed then the motion is known as uniform circular motion.
•    Consider an object moving in a circle with a uniform speed a round a fixed point O as centre.
•    If the object moves from A to B so that the radius OA moves through an angle q, its angular velocity (w) about O is defined as the rate at which the radius vector sweeps. If t is the time taken by the object to move from A to B then, The unit of the angular velocity is rad s-1.
•    The time taken T by the object to describe the circle once is called the period of circular motion. This is the relation connecting the linear velocity and the angular velocity of the object in circular motion.
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December 26, 2019

Science Glossary - Part 8

magme Guru

SCIENCE GLOSSARY - PART 8

351.    Telescope:    It is a device for collecting and focusing light and other forms of electromagnetic radiation form distant objects.

352.    Temperature:    A measure of the average amount of kinetic energy of the particles in an object

353.    Terminal velocity:    The final, maximum velocity of a falling object.

354.    Theory:    In science, a set of widely accepted explanations of observations and phenomena. A theory is a well-tested explanation that is consistent with all available evidence

355.    Thermal energy:    The energy an object has due to the motion of its particles; the total amount of kinetic energy of particles in an object

356.    Thermometer:    It is a device used measures temperature of hotness.

357.    Thermostat:    It is a device used to keep the temperature in some place with in a set range.

358.    Tide:    It is the rise and fall of sea level due to the gravitational forces of the Moon and Sun.

359.    Transformer:    It is a device whose normal use is to transfer electrical energy with a change in voltage between input and output.

360.    Transistor:    It is a device for controlling the flow of minute electric current. It serves as a rectifier or as an amplifier of current.

361.    Transmission:    The passage of a wave through a medium

362.    Transponder:    It is a transmitter cum-receiver which receive radio signals and retransmits them automatically often at a different frequency after amplification.

363.    Transverse wave:    A type of wave in which the disturbance moves at right angles, or perpendicular, to the direction in which the wave travels.

364.    Troposphere:    It is the lowest part, of the earth’s atmosphere in which most of the weather phenomena occur.

365.    Trough:    The lowest point, or valley, of a wave

366.    UFO:    It is an unidentified Flying Object.

367.    Ultrasonics:    It is the study and application of the sound and vibration produced by ultrasonic pressure waves.

368.    Ultraviolet light:    The part of the electromagnetic spectrum that con- sists of waves with frequencies higher than those of visible light and lower than those of x-rays

369.    Uranium:    Radioactive metallic element (system U) of proton number 92 and relatives atomic mass 238.029.

370.    Vacuum:    A space containing few or no particles of matter

371.    Vaporization:    It is the change of state of a substance from liquid to vapour.

372.    Variable:    Any factor that can change in a controlled experiment, observation, or model

373.    Velocity:    It is the speed of an object in a given direction, or the rate of change of an object’s displacement.

374.    VHF:    It is very High frequency referring to radio waves that have very short wavelengths.

375.    Vibration:    A rapid, back-and-forth motion.

376.    Viscosity:    Resistance of fluids (liquids and gases) to flow. It is caused by friction between the fluid molecules moving against each other.

377.    Visible light:    The part of the electromagnetic spectrum that consists of waves detectable by the human eye

378.    Voltage:    It is the electrical pressure or potential difference measured in volts.

379.    Voltmeter:    It is an electrical instrument which measures voltage.

380.    Volume:    An amount of three-dimensional space, often used to describe the space that an object takes up.

381.    Vortex:    It is intense circular or whirling motion of a fluid.

382.    Warhead:    It is the part of a missile, usually placed at the tip. Containing a chemical explosive or incendiary charge and a mechanism for setting it off. It may also carry a nuclear device.

383.    Water cycle:    It is the continuous movement water between the ocean, atmosphere and the land. Water from the ocean evaporates by Sun’s heat and enters the atmosphere as water vapour. The water vapour condenses and comes down as rain from where it flows through streams and rivers into the ocean, thus completing the cycle.

384.    Watt:    It is the unit or power, the rate of energy transfer.

385.    Wave:    A disturbance that transfers energy from one place to another without requiring matter to move the entire clistance

386.    Wavelength:    The distance from one wave crest to the next crest; the distance from any part of one wave to the identical part of the next wave.

387.    Wedge:    A simple machine that has a thick end and a thin end. A wedge is used to cut, split, or pierce objects, or to hold objects together

388.    Weight:    The force of gravity on an object

389.    Wheel and axle:    A simple machine that is a wheel attached to a shaft, or axle

390.    Work:    The use of force to move an object over a distance

391.    X-rays:    The part of the electromagnetic spectrum that consists of waves with high frequencies and high energies; electromagnetic waves with frequencies ranging from more than 1016 hertz to more than 1021 hertz
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December 26, 2019

Science Glossary - Part 7

Magme Guru

SCIENCE GLOSSARY - PART 7

301.    Resistance:    The property of a material that determines how easily a charge can move through it. Resistance is measured in ohms

302.    Resistor:    An electrical device that slows the flow of charge in a circuit

303.    Resonance:    The strengthening of a sound wave when it com- bines with an object’s natural vibration.

304.    Respiration:    The exothermic process by which living things re- lease energy from glucose and oxygen and produce carbon dioxide and water.

305.    Retina:    A light-sensitive membrane at the back of the inside of the eye

306.    Retine:    It is the inner layer at the back of the vertebrate eye, which contains light-sensitive cells and nerve fibres.

307.    Robot:    It is a kind of machine that can do jobs without human help.

308.    Rocket:    It is a projectile driven by the reaction of gases produced by a fast-burning fuel.

309.    Satellite:    It is a kind of spacecraft.

310.    Satellite dish:    It is a kind of aerial.

311.    Saturated:    Containing the maximum amount of a solute that can be dissolved in a particular solvent at a given temperature and pressure

312.    Scattering:    The spreading out of light rays in all directions as particles reflect and absorb the light
313.    Screw:    A simple machine that is an inclined plane wrapped around a cylinder. A screw can be used to raise and lower weights as well as to fasten objects

314.    Second:    A unit of time equal to one-sixtieth of a minute

315.    Seismograph:    It is an instruments that amplifies and record small movements of the ground caused by earthquakes or explosions.

316.    Semiconductor:    Crystalline material with an electrical conductivity between that of metals (good) and insulators (poor).

317.    Sensor:    It is a device that takes in and reacts to some kind of input energy and out puts a related electrical signal.

318.    Series circuit:    A circuit in which current follows a single path. Each device that is wired in a series circuit shares a path to and from the voltage source

319.    Shaft:    It is a rod which rotates and is connected to the axis of a wheel or a gear.

320.    Short circuit:    It is the accidental or deliberate joining of two parts of an electric circuit by a conductor of less resistance that allows an excessive current to flow, usually blowing a fuse.

321.    Silicon chip:    It is a kind of crystal.

322.    Simple machine:    One of the basic machines on which all other me- chanical machines are based. The six simple machines are the lever, inclined plane, wheel and axle, pulley, wedge, and screw

323.    Siphon:    It is a curved pipe or tube and is used to move liquids from one container to another.

324.    Solar cell:    A type of technology in which light-sensitive materials convert sunlight into electrical energy

325.    Solar energy:    It is energy derived from the sun’s radiation.

326.    Solder:    It is an alloy and is used to join together wires and electronics components.

327.    Solid:    Matter that has a definite shape and a definite volume. The molecules in a solid are in fixed positions and are close together

328.    Solstice:    One of the two times of each year when the sun reaches its maximum northerly or southerly position among the stars. In the northern hemisphere, the summer solstice on June 21, is the longest day of the year and winter solstice on December 21 is the shortest day of the year.

329.    Solubility:    The amount of solute that dissolves in a certain amount of a solvent at a given temperature and pressure to produce a saturated solution

330.    Solute:    In a solution, a substance that is dissolved in a solvent

331.    Solution:    A mixture of two or more substances that is identical throughout; a homogeneous mixture

332.    Solvent:    In a solution, the substance that dissolves a solute and makes up the largest percentage of a solution

333.    Sonar:    Instruments that use echolocation to locate objects underwater; acronym for “sound navigation and ranging"

334.    Sound:    A type of wave that is produced by a vibrating object and that travels through matter

335.    Sound barrier:    It is the point at which an aircraft attains the speed of sound.

336.    Spark:    A high energy discharge through a gas that lasts for a very short time, it is accompanied by a flash of light and a sharp crackling noise.

337.    Specific heat:    The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius

338.    Spectrometer:    It is an instrument used to study the composition of light emitted by a source.

339.    Speed:    A measure of how fast something moves through a particular distance over a definite time period.Speed is distance divided by time

340.    Speed of light:    It is the speed at which light travels through emply space. Its value is  299,792, 458 metres per second.

341.    Speed of sound:    It is the speed at which sound travels through a medium, such as air on water. In air at a temperature of 00c, the speed of sound is 331 metres per second.

342.    States of matter:    The different forms in which matter can exist. Three familiar states are solid, liquid, and gas

343.    Static charge:    The buildup of electric charge in an object caused by the uneven distribution of charged particles

344.    Sublimation:    The process by which a substance changes directly from its solid state to its gas state without becoming a liquid first. 

345.    Substance:    Matter of a particular type. Elements, compounds, and mixtures are all substances

346.    Superconductor:    It is a substance which has no electrical resistance.

347.    Supersonic:    It means faster that the speed of sound.

348.    Suspension:    A mixture in which the different parts are identifiable as separate substances; a heterogeneous mixture

349.    System:    A group of objects or phenomena that interact. A system can be as simple as a rope, a pulley, and a mass. It also can be as complex as the interaction of energy and matter in the four parts of the Earth system.

350.    Technology:    The use of scientific knowledge to solve problems or engineer new products, tools, or processes.
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Science Glossary - Part 6
December 26, 2019

Science Glossary - Part 6

  SCIENCE GLOSSARY - PART 6

251.    Particle:    A very small piece of matter, such as an atom, molecule, or ion

252.    Pascal:    The unit used to measure pressure. One pascal is the pressure exerted by one newton of force on an area of one square meter, or one N/m2
253.    Period:    A horizontal row in the periodic table of the elements. Elements in a period have varying properties

254.    Periodic table:    A table of the elements, arranged by atomic number, that shows the patterns in their properties

255.    Periscope:    It is an optical instrument designed for observation from a concealed position such as from a submerged submarine.

256.    Ph:    The concentration of hydrogen ions in a solution; a measurement of acidity.

257.    Photon:    It is a particle which has been invented by scientist to explain how light behaves.

258.    Photosynthesis:    In green plants, the endothermic process in which light is absorbed and used to change carbon dioxide and water into glucose and oxygen.

259.    Physical change:    A change in a substance that does not change the substance into a different one.

260.    Physical property:    A characteristic of a substance that can be observed without changing the identity of the substance.

261.    Physics:    It is the branch of science concerned with the ultimate laws that govern the structure of the universe and the forms of matter and energy and their interactions.

262.    Piston:    It is a part of a machine, it is fitted inside a cylinder and moves back wards and forwards.

263.    Pitch:    The quality of highness or lowness of a sound. Pitch is associated with the frequency of a sound wave- the higher the frequency, the higher the pitch.

264.    Plastic:    A polymer that can be molded or shaped

265.    Plutonium:    It is a radioactive metallic element (symbol Pu) of proton number 94 and relative atomic mass 239.13.

266.    Polar covalent bond:    The unequal sharing of electrons between two at- oms that gives rise to negative and positive regions of electric charge
267.    Polarization:    A way of filtering light so that all of the waves vibrate in the same direction

268.    Pole:    It is a region of a magnetic field where the force is strongest. Most bar magnets have two poles.

269.    Pollution:    The effect on the surface of the Earth of poisonous or harmful substances that makes life less safe or pleasant for living organisms.

270.    Polymer:    A very large carbon-based molecule made of smaller, repeating units

271.    Position:    An object’s location

272.    Potential energy:    It is stored energy.

273.    Potential energy:    Stored energy; the energy an object has due to its position, molecular arrangement, or chemical composition

274.    Power:    The rate at which work is done.

275.    Precipitate:    A solid substance that forms as a result of a reaction between chemicals in two liquids

276.    Pressure:    A measure of how much force is acting on a certain area; how concentrated a force is. Pressure is equal to the force divided by area

277.    Primary colors:    Three colors of light-red, green, and blue-that can be mixed to produce all possible colors.

278.    Primary colour:    A primary colour is one of there different colours of light red. Green and blue colours.

279.    Primary pigments:    Three colors of substances--cyan, yellow, and magenta that can be mixed to produce all possible colors

280.    Prism:    In optics, a triangular block of transport material (plastic glass, silica) commonly used to, bend’ a ray of light or split a beam into its special colours.

281.    Product:    A substance formed by a chemical reaction. A prod- uct is made by the rearrangement of atoms and bonds in reactants

282.    Projectile:    A particle that travels with both horizontal and vertical motion in the Earth’s gravitational field.

283.    Protein:    A macromolecule in living things that is made of smaller molecules called amino acids

284.    Proton:    A positively charged particle located in an atom’s nucleus

285.    Pulley:    A wheel with a grooved rim that turns on an axle; one of the six simple machines

286.    Pupil:    The circular opening in the iris of the eye that con-trols how much light enters the eye

287.    Quantum mechanics:    It is the part of physics that deals with radiation and the movement of atomic particles.

288.    Rader:    An acronym for radio direction and ranging device for locating objects in space, direction finding, and navigation by means of transmitted and reflected high-frequency radio waves.

289.    Radiant heat:    It is energy that is radiated by all warm or hot bodies.

290.    Radiation:    It is a kind of energy which is moving.

291.    Radio waves:    The part of the electromagnetic spectrum that consists of waves with the lowest frequencies

292.    Radioactivity:    It is the spontaneous alteration, or decay, of the nuclei of radioactive atoms, accompanied by the emission of radiation.

293.    Radiocarbon dating:    It is a method of dating organic materials (for example, bone or wood), used in archaeology.

294.    Rainbow:    It is an arch in the sky displaying the colours of the spectrum formed by the refraction and reflection of the Sun’s rays through rain of mist.

295.    Reactant:    A substance that is present at the beginning of a chemical reaction and is changed into a new substance

296.    Reactive:    Likely to undergo a chemical change

297.    Reference point:    A location to which another location is compared
298.    Reflection:    The throwing back or deflection of waves, such as light or sound waves, when they hit a surface.

299.    Refraction:    It is the bending of waves of light, heat or sound when is passes from one medium to another.

300.    Relativity theory:    A theory that described matter, space and time and how they relate to each other.
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Science Glossary - Part 5
December 26, 2019

Science Glossary - Part 5

 SCIENCE GLOSSARY - PART 5

201.    Mach number:    It is a measure of the speed of an object, specially an aircraft. If the Mach number exceeds one, the object is said to be moving at a supersonic speed.

202.    Machine:    Any device that makes doing work easier

203.    Magnet:    An object that attracts certain other materials, particularly iron and steel

204.    Magnetic domain:    A group of atoms whose magnetic fields align, or point in the same direction. Magnetic materials have magnetic domains, whereas nonmagnetic materials do not.

205.    Magnetic field:    An area surrounding a magnet within which the magnet can exert a force. Magnetic fields are concentrated into a pattern of lines that extend from the magnet’s north pole to its south pole
206.    Magnetic pole:    One of two ends of a magnet where the magnetic force is the strongest. Every magnet has two poles

207.    Magnetism:    The force exerted by a magnet. Opposite poles of two magnets attract, or pull together, whereas like poles of two magnets repel, or push apart

208.    Manometer:    An instrument for measuring the pressure of liquids (including human blood pressure) or gases.

209.    Mass:    A measure of how much matter an object is made of.

210.    Matter:    Anything that has mass and volume. Matter exists ordinarily as a solid, a liquid, or a gas

211.    Mechanical advantage:    The number of times a machine multiplies the input force; output force divided by input force

212.    Mechanical energy:    A combination of the kinetic energy and potential energy an object has

213.    Mechanical wave:    A wave, such as a sound wave or a seismic wave, that transfers kinetic energy through matter

214.    Mechanics:    It is the study of movement of material bodies.

215.    Medium:    A substance through which a wave moves.

216.    Meridian:    It is an imaginary circle passing through both the poles of a celestial sphere, It is also the imaginary plane passing through the Earth’s axis.

217.    Metal:    An element that tends to be shiny, easily shaped, and a good conductor of electricity and heat.

218.    Metallic bond:    A certain type of bond in which nuclei float in a sea of electrons.

219.    Metalloid:    An element that has properties of both metals and nonmetals.

220.    Meteorology:    It is the study of climate and weather patterns, with the aim of trying to explain, predict and change them.

221.    Mica:    It is a group of silicate minerals having layered structure.
222.    Microscope:    It is an instrument for magnification with high resolution for detail.

223.    Microwaves:    Part of the electromagnetic spectrum that consists of waves with higher frequencies than radio waves, but lower frequencies than infrared waves

224.    Mirage:    It is the illusion seen in hot climate of water on the horizon, or of distant objects being enlarged.

225.    Missile:    It is guided unmanned weapon which is usually propelled by a rocked.

226.    Mixture:    A combination of two or more substances that do not combine chemically but remain the same individual substances. Mixtures can be separated by physical means

227.    Moderator:    It is a substance that is used to slow down neutrons emitted in a nuclear fission reaction.

228.    Molecule:    A group of atoms that are held together by covalent bonds so that they move as a single unit

229.    Molecule:    it is a group of one or more atoms bonded together, a basic participle of matter.

230.    Momentum:    A measure of mass in motion. The momentum of an object is the product of its mass and velocity

231.    Momentum:    It is a property dependent on the mass and velocity of a body.

232.    Monomer:    One of many small, repeating units linked together to form a polymer

233.    Motion:    A change of position over time

234.    Nanotechnology:    The science and technology of building electronic circuits and devices from single atoms and molecules

235.    Nautical mile:    It is a unit of measurement, it measures distances across seas and oceans.

236.    Net force:    The overall force acting on an object when all of the forces acting on it are combined

237.    Neutral:    Describing a solution that is neither an acid nor a base. A neutral solution has a ph of 7.

238.    Neutron:    A particle that has no electric charge and is located in an atom’s nucleus.

239.    Nonmetal:    An element that is not a metal and has properties generally opposite to those of a metal.

240.    Nuclear fission:    it is the process whereby an atomic nucleus breaks up with the emissions of several neutrons.

241.    Nuclear reactor:    It is the central component of a nuclear power station that generated nuclear energy under controlled conditions for use as a source of electrical power.

242.    Nuclear waste:    It is the radio-active and toxic by-products of the nuclear-energy and nuclear-weapons industries.

243.    Nucleic acid:    One of several carbon-based molecules that carry an organism’s genetic code. One of the nucleic acids DNA- contains the information needed to construct proteins

244.    Nucleus:    The central region of an atom where most of the atom’s mass is found in protons and neutrons

245.    Ohm:    The SI unit of electrical resistance, named after Georg Simon Ohm.

246.    Opaque:    It described a substance which does not allow light to pass through it.

247.    Optics:    It is the study of nature and properties of light.

248.    Organic compound:    A compound that is based on carbon

249.    Oscillation:    One completer to and-fro movement of a vibrating object or system.

250.    Parallel circuit:    A circuit in which current follows more than one path. Each device that is wired in a parallel circuit has its own path to and from the voltage source

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Science Glossary - Part 4
December 26, 2019

Science Glossary - Part 4

 SCIENCE GLOSSARY - PART 4

151.    Horizontal:    Parallel to the horizon; level.

152.    Horse power (hp):    It is a practical unit of power which equal to 550 foot-pound per second or 746 watts.

153.    Hurricane:    It is a powerful whirling tropical storm that measures 320 to 480 kilometres in diameter.

154.    Hydraulics:    It is the branch of physics that deals with the behaviour of liquids at rest and in motion.

155.    Hydrocarbon:    A compound that contains only carbon and hydrogen

156.    Hydrometer:    It is an instrument used to measures the relatives density of liquids (the density compared with that of water).

157.    Hydrosphere:    The water of the earth, ocean lakes, rivers and glaciers that cover about three-fourths of the earth’s surface.

158.    Hygrometer:    It is an instrument used to measure the amount of water vapour in the air.

159.    Hypersonic:    The sound waves which have frequencies above 500 megahertz

160.    Hypersonic speed:    The speed of an object greater than about five times the speed of sound in the fluid through which the object is moving.

161.    Hypothesis:    A tentative explanation for an observation or phenomenon. A hypothesis is used to make testable predictions.

162.    Imaging:    It is a technique by which electronics data collected by various means is converted into visual image by use of computers.

163.    Incandescence:    The production of light by materials having high temperatures & Light produced by an incandescent object

164.    Inclined plane:    A simple machine that is a sloping surface, such as a ramp

165.    Induction:    The build-up of a static charge in an object when the object is close to, but not touching, a charged object.

166.    Inertia:    The tendency of an object to remain in a state of rest of uniform motion until an external force is applied, as stated by Newton’s first law of motion.

167.    Inertia:    The resistance of an object to a change in the speed or the direction of its motion

168.    Information Technology:    It is a scientific subject, the study of how to collect, use, move, store and display information.

169.    Infrared light:    Part of the electromagnetic spectrum that consists of waves with frequencies between those of microwaves and visible light

170.    Inorganic compound:    A compound that is not considered organic. All com- pounds that do not contain carbon are inorganic, as are some types of carbon-containing compounds.

171.    Insulation:    It is the process by which the passage of electricity, heat or sound is prevented through a material.

172.    Insulator:    A material that does not transfer energy easily & A material that does not transfer electric charge easily

173.    Intensity:    The amount of energy of a wave, per wavelength. Intensity is associated with the amplitude of a sound wave and with the quality of loudness produced by the sound wave

174.    Interference:    The meeting and combining of waves; the adding or subtracting of wave amplitudes that occurs as waves overlap

175.    Ion:    An atom or group of atoms that has a positive or negative electric charge.

176.    Ionic bond:    The electrical attraction between a negative ion and a positive ion.

177.    Isomer:    Any of two or more compounds that contain the same atoms but that have different structures

178.    Isotopes:    These are atoms of an element having the same atomic number but different atomic weights.

179.    Jet lag:    It is a state of feeling unwell and exhausted experienced by air travellers when they cross several time zones in a relatively short time.

180.    Joule:    A unit used to measure energy and work. One calorie is equal to 4. 18 joules of energy; one joule of work is done when a force of one newton moves an object one meter.

181.    Kilowatt kw:    A unit of measurement for power equal to 1000 watts.

182.    Kilowatt-hour kwh:    The unit of measurement for electrical energy equal to one kilowatt of power over a one-hour period

183.    Kinetic energy:    It is a form of energy possessed by moving bodies. It is contrasted with potential energy.

184.    Kinetic theory of matter :    A theory stating that all matter is made of particles in motion

185.    Knot:    It is a unit for measuring ship’s speed.

186.    Laser:    The name stands for Light Amplification by stimulated Emission of Radiation. A device able to produce an intension narrow beam of radiation.

187.    Latent heat:    It is the heat required to change the state of a substance (for example, from solid to liquid) without changing its temperature.

188.    Latitude:    It is the distance of a point on the earth’s surface from the equator.

189.    Law:    In science, a rule or principle describing a physical relationship that always works in the same way under the same conditions. The law of conservation of energy is an example.

190.    Law of conservation of energy:    A law stating that no matter how energy is transferred or transformed, it continues to exist in one form or another

191.    Law of conservation of momentum:    A law stating that the amount of momentum a sys- tem of objects has does not change as long as there are no outside forces acting on that system

192.    Law of reflection:    A law of physics stating that the angle at which light strikes a surface (the angle of incidence) equals the angle at which it reflects off the surface (the angle of reflection). 

193.    Lens:    A transparent optical tool that refracts light

194.    Lever:    A solid bar that rotates, or turns, around a fixed point (fulcrum); one of the six simple machines

195.    Lighting conductor:    It is a conductor of electricity installed in a structure to save it from damage.

196.    Light-year:    It is a unit of distance used in astronomy. It is defined as the distance light travels through space in one year. Light travels at 300,000 km per second.

197.    Lipid:    A type of carbon-based molecule in living things. Lipids include fats and oils used for energy or as structural materials.

198.    Liquid:    Matter that has a definite volume but does not have a defmite shape. The molecules in a liquid are close together but not bound to one another.

199.    Longitudinal wave :    A type of wave in which the disturbance moves in the same direction that the wave travels

200.    Luminescence:    The production of light without the high tempera- tures needed for incandescence
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Science Glossary - Part 3
December 26, 2019

Science Glossary - Part 3

SCIENCE GLOSSARY - PART 3

101.    Electron:    It is one of the basic particles of matter.

102.    Electronic:    Operating by means of an electrical signal. An electronic device is a device that uses electric current to represent coded information

103.    Element:    It is substance that cannot be split chemically into simpler substances.

104.    Endothermic reaction:    A chemical reaction that absorbs energy

105.    Energy:    The ability to do work or to cause a change. For example, the energy of a moving bowling ball knocks over pins; energy from food allows animals to move and to grow; and energy from the Sun heats Earth’s surface and atmosphere, which causes air to move.

106.    Energy efficiency:    A measurement of usable energy after an energy conversion; the ratio of usable energy to the total energy after an energy conversion

107.    Enzyme:    A type of protein that is a catalyst for chemical reactions in living things

108.    Epicentre:    It is a point directly above the true centre of disturbing from which the shock wavers of an earthquakes apparently radiate.

109.    Escape speed:    It is the speed of an object leaving the surface of a planet, such that it just escapes the gravitational pull.

110.    Escape velocity:    It is the minimum velocity with which an object must be projected for it to escape from the gravitational pull of a planetary body.

111.    Evaporation:    A process by which a substance changes from its liquid state to its gas state by random particle movement.Evaporation usually occurs at the surface of a liquid over a wide range of temperatures.

112.    Exothermic reaction:    A chemical reaction that releases energy

113.    Experiment:    An organized procedure to study something under controlled conditions

114.    Fallout:    These are the radio-active substance deposited upon the surface of the earth after the explosion of a nuclear weapon of mishap at a nuclear reactor.

115.    Fibre optics:    It is branch of physics dealing with the transmission of light and images though glass or plastic known as optical fibres.

116.    Field:    An area around an object where the object can apply a force-such as gravitational force, magnetic force, or electrical force-on another object without touching it

117.    Filament:    It is a thin, high resistance wire as in an electric light bulb.

118.    Filter:    It is a kind of apparatus which helps to separate a mixture.

119.    Fleming’s rules:    These are memory aids for the directions of the magnetic field, current and motion in an electric generator or motor, using one’s fingers.

120.    Fluid:    A substance that can flow easily, such as a gas or a liquid

121.    Fluorescence:    A phenomenon in which a material absorbs electro- magnetic radiation of one wavelength and gives off

122.    Fly wheel:    It is a heavy wheels connected to the shaft of an engine. It maintains the smooth rotation of the shaft because of its high inertia.

123.    Focal length:    The distance from the center of a convex lens to its focal point

124.    Focal point:    The point at which parallel light rays reflected from a concave mirror come together; the point at which parallel light rays refracted by a convex lens come together

125.    Force:    A push or a pull; something that changes the motion of an object

126.    Forensic science:    It carries out test and searches for clues to help the police and lawyers.

127.    Fossil fuel:    Any fuel produced by the slow decay of dead things and which, therefore, is not renewable.

128.    Free fall:    It is the state in which a body is falling freely under the influence of gravity, as in free-fall parachuting.

129.    Freezing:    The process by which a substance changes from its liquid state into its solid state

130.    Freezing point:    The temperature at which a substance changes from its liquid state to its solid state through freezing

131.    Frequency:    The number of waves that pass a fixed point in a given amount of time, usually one second; the num- ber of cycles per unit time

132.    Friction:    A force that resists the motion between two surfaces in contact

133.    Friction:    It is the force that opposes the relative motion of two bodies in contact.

134.    Fulcrum:    A fixed point around which a lever rotates.

135.    Fuse:    It is a thin piece of wire, a part of an electric circuit.

136.    Galvanometer:    It is a sensitive instrument for detecting or measuring small electric currents.

137.    Gamma rays:    Part of the electromagnetic spectrum that consists of waves with the highest frequencies; electromagnetic waves with frequencies ranging from more than 1019 hertz to more than 1024 hertz

138.    Gas:    It is a state of matter which has no fixed shape or volume and always fills the whole of the space in which it is contained.

139.    Geiger counter:    It is a device which measures radiation.

140.    Generator:    It is a machine that transfers kinetic energy to electricity.

141.    Gravity:    The force that objects exert on each other because of their mass

142.    Greenhouse effect:    It is a phenomenon of the Earth’s atmosphere by which solar radiation, absorbed by the Earth and re-emitted from the surface, is prevented from escaping by gases, mainly carbon dioxide in the air.

143.    Grid:    It is the network by which electricity is generated and distributed over a region or country.

144.    Grounding:    The creation of a harmless, low-resistance path-a ground-for electricity to follow. Grounding is an important electrical safety procedure.

145.    Group:    A vertical column in the periodic table of the elements. Elements in a group have similar properties

146.    Half-life:    The amount of time it takes for half of the nuclei of a radioactive isotope to decay into atoms of another element.

147.    Heat:    The flow of energy from an object at a higher temperature to an object at a lower temperature OR Energy that is transferred from a warmer object to a cooler object

148.    Hectare:    It is a unit of measurement which measures area.

149.    Hertz:    It is a unit of measurement which measures the frequency of vibrations.

150.    Hexagon:    It is a flat shape which has six sides.
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Science Glossary - Part 2
December 26, 2019

Science Glossary - Part 2

SCIENCE GLOSSARY - PART 2

51.    Circuit breaker:    It is a safety switch that automatically cuts off the current when there is an overland.

52.    Climate:    It is the long-term pattern of weather in a region.

53.    Coefficient:    The number before a chemical formula that indicates how many molecules are involved in a chemical reaction

54.    Collision:    A situation in which two objects in close contact exchange energy and momentum

55.    Compass:    it is an instrument which helps people to find their way from one place to another.

56.    Compound:    A substance made up of two or more different types of atoms bonded together

57.    Compound machine:    A machine that is made up of two or more simple machines.

58.    Concave:    Curved inward toward the center, like the inside of a spoon

59.    Concentration:    The amount of solute dissolved in a solvent at a given temperature.

60.    Condensation:    The process by which a gas becomes a liquid

61.    Conduction:    The process by which energy is transferred from a warmer object to a cooler object by means of physical contact.

62.    Conductor:    A material that transfers energy easily & A material that transfers electric charge easily

63.    Convection:    A process by which energy is transferred in gases and liquids,occurring when a warmer, less dense area of  gas or liquid is pushed up by a cooler, more dense area of the gas or liquid

64.    Convex:    Curved outward, like the underside of a spoon

65.    Cooling tower:    It is part of a power station.

66.    Cornea:    A transparent membrane that covers the eye

67.    Coulomb:    It is a unit of electric charge.

68.    Covalent bond:    A pair of electrons shared by two atoms

69.    Crest:    The highest point, or peak, of a wave

70.    Cube:    It has a solid shape, it has six square sides which are all the same size.

71.    Curie:    It is a unit of radio-activity.

72.    Cycle:    Noun : A series of events or actions that repeat them- selves regularly; a physical and/or chemical process in which one Verb: To move through a repeating series of events or actions.material continually changes locations and/or forms. Examples include the water cycle, the carbon cycle, and the rock cycle.

73.    Decibel:    It is a unit of measurement. It measures the loudness of sound.

74.    Decibel db:    The unit used to measure the intensity of a sound wave

75.    Degree:    Evenly divided units of a temperature scale

76.    Density:    A property of matter representing the mass per unit volume

77.    Diffraction:    The spreading out of waves as they pass through an opening or around the edges of an obstacle.

78.    Diffuse reflection:    The reflection of parallel light rays in many different directions

79.    Diffusion:    It is the movement of atoms and molecules in gases and liquids.

80.    Digital:    It is a term meaning coded as number.

81.    Dilute:    Having a low concentration of solute

82.    Diode:    It is a term part of some electric circuits.

83.    Direct current DC:    Electric current that flows in one direction only

84.    Docking:    It is the mechanical coupling of two or more spacecraft.

85.    Doppler effect:    The change in perceived pitch that occurs when the source or the one who hears the sound is moving

86.    Dynamo:    It is a simple generator, or machine for transforming mechanical energy into electrical energy.

87.    Echo:    It is a sound which is reflected.
88.    Eclipse:    it is passage of an astronomical body through the shadow of another.

89.    Elastically:    It is an elastic substance which obey Hooke’s law. This means that if we stretch or compress a sample, it deforms (stains) in proportion. It returns to its original state when the stress ceases.

90.    Electric cell:    A device that produces electric current using the chemical or physical properties of different materials.

91.    Electric charge:    A property that allows one object to exert an electric force on another object without touching it. Electric charge can be positive or negative: positive charge is a property of the proton, while negative charge is a property of the electron

92.    Electric current:    A continuous flow of electric charge, which is mea- suredin amperes

93.    Electric field:    An area surrounding a charged object, within which the object can exert an electric force on another object without touching it

94.    Electric potential:    The amount of potential energy per unit charge that a static charge or electric current has. Electric potential is measured in volts and is often called voltage.

95.    Electric power:    The rate at which electrical energy is generated from, or converted into, another source of energy, such as kinetic energy

96.    Electromagnet:    A magnet that consists of a piece of iron or steel inside a coil of current-carrying wire

97.    Electromagnet:    It is a special coil of wire.

98.    Electromagnetic spectrum :    The range of all electromagnetic frequencies, in- cluding the following types (from lowest to highest frequency): radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays

99.    Electromagnetic wave :    A type of wave, such as a light wave or radio wave, that does not require a medium to travel; a disturbance that transfers energy through a field

100.    Electromagnetism:    Magnetism that results from the flow of electric charge
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