Physics Definitions

Question 1

Resultant vector

Answer 1

the vector sum of two or more vectors, i.e. a single vector having the same effect as two or more vectors together.

Question 2

normal force, N

Answer 2

the force or the component of a force which a surface exerts
on an object in contact with it, and which is perpendicular to the surface.

Question 3

frictional force, f

Answer 3

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

Question 4

static friction

Answer 4

the force that opposes the tendency of motion of a stationary object relative to a surface.

Question 5

kinetic friction

Answer 5

the force that opposes the motion of a moving object relative to a surface.

Question 6

Newton’s first law of motion:

Answer 6

A body will remain in its state of rest or motion at constant velocity unless a non-zero resultant/net force acts on it.

Question 7

Newton’s second law of motion:

Answer 7

When a resultant/net force acts on an object, the object will accelerate in the direction of the force at an acceleration directly proportional to the force and inversely proportional to the mass of the object.

Question 8

Newton’s third law of motion:

Answer 8

When object A exerts a force on object B, object B
SIMULTANEOUSLY exerts an oppositely directed force of equal magnitude on object A.

Question 9

Newton’s law of universal gravitation:

Answer 9

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

Question 10

Weight

Answer 10

the gravitational force, in newton (N), exerted by the Earth on an object.

Question 11

mass

Answer 11

the amount of matter in a body measured in kilogram (kg).

Question 12

weightlessness

Answer 12

the sensation experienced when all contact forces are
removed

Question 13

wave front

Answer 13

an imaginary line joining points on a wave that are in phase.

Question 14

Huygens’ principle:

Answer 14

Every point of a wave front serves as a point source of spherical, secondary waves that move forward with the same speed as the wave.

Question 15

diffraction

Answer 15

the ability of a wave to spread out in wave fronts as the wave passes through a small aperture or around a sharp edge.

Question 16

Coulomb’s law:

Answer 16

The magnitude of the electrostatic force exerted by two point charges (Q1 and Q2) on each other is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance (r)
between them.

Question 17

electric field

Answer 17

a region in space in which an electric charge experiences a
force. The direction of the electric field at a point is the direction that a positive test charge would move if placed at that point.

Question 18

Ohm’s law

Answer 18

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

Question 19

power

Answer 19

rate at which work is done or energy is transferred.

Question 20

kilowatt-hour (kWh)

Answer 20

to the use of 1 kilowatt of electricity for
1 hour.

Question 21

Faraday’s law of electromagnetic induction:

Answer 21

The magnitude of the induced emf across the ends of a conductor is directly proportional to the rate of change in the magnetic flux linkage with the conductor.

Question 22

Electric field strength at a point

Answer 22

The electrostatic force experienced per unit positive charge placed at that point.