All IEB Definitions for Physics

Question 1

Vector

Answer 1

a physical quantity that has both magnitude and direction.

Question 2

Scalar

Answer 2

a physical quantity that has magnitude only.

Question 3

Resultant vector

Answer 3

the single vector which has the same effect as the original vectors acting together.

Question 4

Distance

Answer 4

the length of path travelled.

Question 5

Displacement

Answer 5

a change in position.

Question 6

Speed

Answer 6

the rate of change of distance.

Question 7

Velocity

Answer 7

the rate of change of position
OR
the rate of displacement
OR
the rate of change of displacement.

Question 8

Acceleration

Answer 8

the rate of change of velocity.

Question 9

Weight

Answer 9

the gravitational force the Earth exerts on any object on or near its surface.

Question 10

Gravitational field

Answer 10

the force acting per unit mass.

Question 11

Normal force

Answer 11

the perpendicular force exerted by a surface on an object in contact with it.

Question 12

Friction force due to a surface (Frictional force)

Answer 12

the force that opposes the motion of an object and acts parallel to the surface with which the object is in contact with.

Question 13

Newton’s first law

Answer 13

an object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force.

Question 14

Inertia

Answer 14

the property of an object that causes it to resist a change in its state of rest or uniform motion.

Question 15

Newton’s second law

Answer 15

when a net force, Fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass.

Question 16

Newton’s third law

Answer 16

when object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A.

Question 17

Newton’s law of universal gravitation

Answer 17

every particle with mass in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.

Question 18

Linear momentum

Answer 18

the product of the mass and velocity of the object.

Question 19

Newton’s second law in terms of momentum

Answer 19

the net force acting on an object is equal to the rate of change of momentum.

Question 20

Impulse

Answer 20

the product of the net force and contact time.

Question 21

Law of conservation of linear momentum

Answer 21

the total linear momentum of an isolated system remains constant (is conserved).

Question 22

Elastic collision

Answer 22

a collision in which both momentum and kinetic energy are conserved.

Question 23

Inelastic collision

Answer 23

a collision in which only momentum is conserved.

Question 24

Work done on an object by a force (Work)

Answer 24

the product of the displacement and the component of the force parallel to the displacement.

Question 25

Gravitational potential energy

Answer 25

the energy an object possesses due to its position relative to a reference point.

Question 26

Kinetic energy

Answer 26

the energy an object has as a result of the object’s motion.

Question 27

Work-energy theorem

Answer 27

the work done by a net force on an object is equal to the change in the kinetic energy of the object.

Question 28

Mechanical energy

Answer 28

the sum of gravitational potential and kinetic energy at a point.

Question 29

Law of conservation of energy

Answer 29

the total energy in a system cannot be created nor destroyed, only transformed from one form to another.

Question 30

Principle of conservation of mechanical energy

Answer 30

in the absence of air resistance or any external forces, the mechanical energy of an object is constant.

Question 31

Power

Answer 31

the rate at which work is done or the rate at which energy is transferred.

Question 32

Watt

Answer 32

one watt is defined as the power when one joule of work is done in one second.

Question 33

Efficiency

Answer 33

the ratio of output power to input power.

Question 34

Coulomb’s law

Answer 34

two point charges in free space or air exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between the charges.

Question 35

Magnitude of the electric field at a point

Answer 35

the force per unit positive charge E = F/q where E and F are vectors.

Question 36

Potential difference

Answer 36

the work done per unit positive charge.
V = W/Q

Question 37

Current

Answer 37

the rate of flow of charge.
I = q/t

Question 38

Ohm’s law

Answer 38

current through a conductor is directly proportional to the potential difference across the conductor at constant temperature.

Question 39

Resistance

Answer 39

a material’s opposition to the flow of electric current.

Question 40

Electromotive force (emf)

Answer 40

the total energy supplied per coulomb of charge by the cell.

Question 41

Magnetic flux linkage

Answer 41

the product of the number of turns on the coil and the flux through the coil (NΦ).

Question 42

Faraday’s law of electromagnetic induction

Answer 42

the emf induced is directly proportional to the rate of change of magnetic flux (flux linkage).

Question 43

Lenz’s Law

Answer 43

the induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux.

Question 44

Diode

Answer 44

a component that only allows current to flow in one direction.

Question 45

Threshold (cut-off) frequency

Answer 45

the minimum frequency of incident radiation at which electrons will be emitted from a particular metal.

Question 46

Work function

Answer 46

the minimum amount of energy needed to emit an electron from the surface of a metal.