Main Definitions

Question 1

Scalars

Answer 1

Quantity that can be described by just a size and unit

Question 2

Vectors

Answer 2

A quantity that is described with size, unit and direction

Question 3

Acceleration

Answer 3

The rate of change of velocity

Question 4

Velocity

Answer 4

The rate of change of displacement

Question 5

Projectile

Answer 5

An object that moves with constant horizontal velocity whilst simultaneously accelerating vertically due to gravity

Question 6

Newtons 1st law

Answer 6

An object will remain at constant velocity unless acted upon by an unbalanced force

Question 7

Newtons 2nd law

Answer 7

F=Ma

Question 8

Newtons 3rd law

Answer 8

If A exerts a force on B then B will exert an equal but opposite force on A

Question 9

Elastic collisions

Answer 9

Both momentum and kinetic energy are conserved. The kinetic energy before and after the collision is the same

Question 10

Inelastic collisions

Answer 10

Momentum is conserved but kinetic energy isn’t. The kinetic energy after the collision is either greater or less than the kinetic energy before.

Question 11

Impulse

Answer 11

The change in momentum of an object

Question 12

Einsteins 1st postulate

Answer 12

The speed of light is constant to all observers no matter their velocity

Question 13

Einsteins 2nd postulate

Answer 13

The laws of physics are the same for all freely moving observers

Question 14

Law of conservation of energy

Answer 14

Energy cannot be created of destroyed, only changed from one form into another

Question 15

Length contraction

Answer 15

A stationary observer will observe a moving object to have a shorter length than someone on the moving object

Question 16

Doppler effect (sound)

Answer 16

The change in frequency of a wave caused by relative motion between the source and observer

Question 17

Redshift

Answer 17

Wavelength of light is stretched so the light is seen as towards the red end of the visible spectrum

Question 18

Hubbles law

Answer 18

Galaxies that are moving faster are further away from us as some galaxies are more redshifted than others

Question 19

Coherent source

Answer 19

Waves that have a constant phase relationship

Question 20

Critical angle

Answer 20

The angle of incidence such that the angle of reflection is 90 degrees

Question 21

Irrandence

Answer 21

The power per unit area

Question 22

Volt

Answer 22

One volt is one joule of work done moving one coulomb of charge between 2 points

Question 23

Photoelectric effect

Answer 23

Evidence for the particular model of light
Proves how each photon of light contains a fixed amount of energy

Question 24

Work function

Answer 24

The number of joules of energy is the minimum energy required for photons to be emitted

Question 25

Threshold frequency

Answer 25

Minimum frequency of photons required to give photo emissions

Question 26

Potential difference / voltage

Answer 26

The difference in the amount of energy that charge carriers have between two points in a circuit

Question 27

Power

Answer 27

The energy used per second

Question 28

EMF

Answer 28

The number of joules of energy given to each coulomb of charge which passes through the source