Physical sciences paper 1 definitions

Question 1

normal force

Answer 1

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

Question 2

frictional force

Answer 2

the force that opposes the motion of an object and which
acts parallel to the surface.

Question 3

Static frictional force

Answer 3

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

Question 4

kinetic frictional force

Answer 4

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

Question 5

newton’s first law of motion

Answer 5

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 6

newton’s second law of motion

Answer 6

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

Question 7

newton’s third law of motion

Answer 7

When object A exerts a force on object B, object B exerts a force of equal magnitude in the opposite direction of object A

Question 8

newton’s universal law of gravitation

Answer 8

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

Question 9

weight

Answer 9

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

Question 10

weightlessness

Answer 10

weightlessness is the sensation experienced when all contact forces are removed i.e no external forces touch ones body

Question 11

momentum

Answer 11

as the product of an object’s mass and its velocity

Question 12

linear momentum

Answer 12

A vector quantity with the same direction as the velocity
of the object.

Question 13

Newton’s second law of motion in terms of momentum

Answer 13

The net (or resultant) force acting on an object is equal to the rate of change of momentum of the object in the direction of the net force.

Question 14

Impulse

Answer 14

Is the product of the resultant/net force acting on an object and the time the net force acts on the object.

Question 15

System

Answer 15

A system is a collection of two or more objects that interact with each other

Question 16

Isolated system

Answer 16

A system on which the resultant/net External force is zero

Question 17

the principle of conservation of linear momentum

Answer 17

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

Question 18

Work- energy theorem

Answer 18

The net work done on an object is equal to the change in the object’s kinetic energy.

Question 19

Conservative force

Answer 19

Force for which the work done in moving an object between two points independent of the path taken.

Question 20

Non-Conservative force

Answer 20

Force for which the work done in moving an object between two points depends on the path taken.

Question 21

Principle of conservation of mechanical energy

Answer 21

The total mechanical energy (sum of gravitational potential energy and kinetic energy) in an isolated system remains constant

Question 22

power

Answer 22

The rate at which work is done

Question 23

Gravitational potential energy

Answer 23

The energy an object has because of its position in the gravitational field relative to some reference point.

Question 24

Doppler Effect

Answer 24

as the change in frequency (or pitch) of the sound detected by a listener, because the sound source and the listener have different velocities relative to the medium of sound propagation.

Question 25

Coulomb's law

Answer 25

The magnitude of the electrostatic force exerted by one point charge (Q1) on another point charge (Q2) 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 26

electric field

Answer 26

as a region of 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 27

Electric field strength at a point

Answer 27

The electric field strength at this point is the electrostatic force experienced per unit positive charge placed at that point.

Question 28

Ohm's Law

Answer 28

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

Question 29

power

Answer 29

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

Question 30

emf

Answer 30

the maximum energy supplied by a battery per unit charge passing through it

Question 31

The rms potential difference

Answer 31

is the AC potential difference which dissipates/produces the same amount of energy as an equivalent DC potential difference.

Question 32

The rms current

Answer 32

is the alternating current which dissipates/produces the same amount of energy as an equivalent direct current (DC).

Question 33

photoelectric effect

Answer 33

as the process whereby electrons are ejected from a metal surface when light of suitable frequency is incident on that surface.

Question 34

threshold frequency, fo,

Answer 34

as the minimum frequency of light needed to emit electrons from a certain metal surface.

Question 35

work function, Wo,

Answer 35

as the minimum energy that an electron in the metal needs to be emitted from the metal surface.