(ESSENTIAL) Quantities and units for iGCSE physics (double award)

Question 1

In the equation K.E. = ½mv²

what does the ‘v’ stand for, and what units is it measured in?

Answer 1

Here ‘v’ stands for speed, measured in m/s

Question 2

In the equation F = kx

what does the ‘F’ stand for, and what units is it measured in?

Answer 2

Here ‘F’ stands for a force (extending a spring) measured in Newtons (N)

Question 3

In the equation a = Δv ÷ Δt

what does the ‘a’ stand for, and what units is it measured in?

Answer 3

Here ‘a’ stands for acceleration, measured in m/s²

Question 4

In the equation work done = Fd

what does the ‘d’ stand for, and what units is it measured in?

Answer 4

Here ‘d’ stands for ‘distance moved in the direction of the force.’ It is measured in m.

Question 5

In the equation average speed = total distance travelled ÷ total time taken, what units is average speed measured in?

Answer 5

Average speed is measured in m/s

Question 6

In the equation ρ = m ÷ V

what does the ‘ρ’ stand for, and what units is it measured in?

Answer 6

Here ‘ρ’ stands for density. It is measured in kg/m³.(or occasionally in g/cm³)

Question 7

In the equation W = mg

what does the ‘W’ stand for, and what units is it measured in?

Answer 7

Here ‘W’ stands for ‘weight.’ Since weight is a force, it is measured in Newtons (N)

Question 8

In the equation G.P.E. = mgh

what does ‘G.P.E.’ stand for, and what units is it measured in?

Answer 8

Here ‘G.P.E.’ stands for ‘gravitational potential energy.’ As with all energies, it is measured in Joules. (J)

Question 9

In the equation P = F ÷ A

what does the ‘P’ stand for, and what units is it measured in?

Answer 9

Here ‘P’ stands for pressure. It is measured in Pascals. (Pa)

Question 10

In the equation P₁V₁ = P₂V₂

what does the ‘P₁’ stand for, and what units is it measured in?

Answer 10

P₁stands for ‘initial pressure’. It is measured in Pascals. (Pa)

Question 11

In the equation Moment = Fd

what does the ‘d’ stand for, and what units is it measured in?

Answer 11

Here ‘d’ stands for ‘distance from pivot.’ It is measured in m.

Question 12

In the equation Q = It

what does the ‘Q’ stand for, and what units is it measured in?

Answer 12

Here ‘Q’ stands for charge. It is measured in Coulombs. (C)

Question 13

In the equation V = IR

what does the ‘V’ stand for, and what units is it measured in?

Answer 13

Here ‘V’ stands for voltage. (Sometimes called ‘potential difference.’) It is measured in volts. (V)

Question 14

In the equation ‘power = energy transferred ÷ time’

what is power measured in?

Answer 14

Power is measured in Watts (W)

Question 15

In the equation ‘efficiency = useful energy output ÷ total energy input’ what units is efficiency measured in?

Answer 15

Efficiency is a ratio, so it doesn’t have any units. It can be written as a decimal (without units) or multiplied by 100% and written as a percentage.

Question 16

In the equation P = IV

what does the ‘P’ stand for, and what units is it measured in?

Answer 16

Here ‘P’ stands for ‘power.’ Power is measured in Watts. (W)

Question 17

In the equation v = fλ

what does the ‘v’ stand for, and what units is it measured in?

Answer 17

Here ‘v’ stands for wave speed.’ It is measured in m/s.

Question 18

In the equation f = 1/T

what does the ‘f’ stand for, and what units is it measured in?

Answer 18

Here ‘f’ stands for ‘frequency.’ It is measured in Herz. (Hz)

Question 19

In the equation n = sin(i) ÷ sin (r)

what does the ‘n’ stand for, and what units is it measured in?

Answer 19

‘n’ here stands for ‘refractive index’. Refractive index is a ratio, so it doesn’t have any units.

Question 20

In the equation sin(c) = 1/n

what does the ‘c’ stand for, and what units is it measured in?

Answer 20

Here ‘c’ stands for the ‘critical angle’ of the material. It is measured in degrees. (°)

Question 21

In the equation P = ρgh

what does the ‘h’ stand for, and what units is it measured in?

Answer 21

Here ‘h’ stands for ‘depth below the surface of a liquid.’ Since this is a distance, ‘h’ is measured in metres. (m)

Question 22

In the equation ‘stopping distance = thinking distance + braking distance’, what units is braking distance measured in?

Answer 22

Like all distances, braking distance is measured in metres (m)

Question 23

In the equation v = Δd ÷ Δt

what does the ‘Δt’ stand for, and what units is it measured in?

Answer 23

Here ‘Δt’ stands for ‘change in time.’ It is measured in seconds. (s)

Question 24

In the equation K.E. = ½mv²

what does the ‘m’ stand for, and what units is it measured in?

Answer 24

Here ‘m’ stands for ‘mass’. It is measured in kilograms. (kg)

Question 25

In the equation F = kx | what does the 'k' stand for, and what units is it measured in?

Answer 25

'k' stands for the 'spring constant'. (sometimes called 'force constant') It is measured in N/m (Newtons per meter)

Question 26

In the equation a = Δv ÷ Δt | what does the 'Δv' stand for, and what units is it measured in?

Answer 26

Here 'Δv' stands for change in speed. It is measured in metres per second (m/s)

Question 27

In the equation work done = Fd | what does the 'F' stand for, and what units is it measured in?

Answer 27

'F' stands for force. It is measured in Newtons.

Question 28

In the equation ρ = m ÷ V | what does the 'm' stand for, and what units is it measured in?

Answer 28

Here 'm' stands for mass, in kilograms. (kg)

Question 29

In the equation W = mg what does the 'g' stand for, and what units is it measured in? !!THIS IS ONE OF THE MOST COMMON QUESTIONS AT GCSE!!

Answer 29

Here 'g' stands for gravitational field strength. Its units are N/kg.

Question 30

In the equation G.P.E. = mgh | what does 'h' stand for, and what are its units?

Answer 30

Here 'h' stands for height, measured in metres (m) | N.B. if you are calculating how much G.P.E changes, 'h' is the *change* in height.

Question 31

In the equation P = F ÷ A | what does the 'A' stand for, and what units is it measured in?

Answer 31

'A' stands for 'area.' Its units are metres squared. (m²)

Question 32

In the equation P₁V₁ = P₂V₂ | what does the 'V₁' stand for, and what units is it measured in?

Answer 32

'V₁' stands for 'initial volume.' It is measured in metres cubed. (m³)

Question 33

In the equation Moment = Fd | what units is a 'moment' measured in?

Answer 33

The units of a moment are Nm. (Newton metres)

Question 34

In the equation Q = It | what does the 'I' stand for, and what units is it measured in?

Answer 34

Here 'I' stands for 'current'. It is measured in amps. (A)

Question 35

In the equation V = IR | what does the 'R' stand for, and what units is it measured in?

Answer 35

'R' stands for resistance. It is measured in ohms. (Ω)

Question 36

In the equation 'efficiency = useful energy output ÷ total energy input' what units is total energy input measured in?

Answer 36

Total energy input is measured in Joules. (J)

Question 37

In the equation P = IV | what does the 'I' stand for, and what units is it measured in?

Answer 37

Here 'I' stands for 'current'. It is measured in amps. (A)

Question 38

In the equation v = fλ | what does the 'f' stand for, and what units is it measured in?

Answer 38

Here 'f' stands for frequency, measured in Hertz. (Hz)

Question 39

In the equation f = 1/T | what does the 'T' stand for, and what units is it measured in?

Answer 39

Here 'T' stands for 'time period.' (of a wave or oscillation) It is measured in seconds. (s)

Question 40

In the equation n = sin(i) ÷ sin (r) | what does the 'i' stand for, and what units is it measured in?

Answer 40

Here 'i' stands for the angle of incidence, measured in degrees.

Question 41

In the equation sin(c) = 1/n | what does the 'n' stand for?

Answer 41

Here 'n' stands for the refractive index of a material. Refractive indexes are always 1 or greater. They do not have units.

Question 42

In the equation P = ρgh | what does the 'P' stand for, and what units is it measured in?

Answer 42

Here 'P' stands for 'pressure'. It is measured in Pascals. (Pa)

Question 43

In the equation 'stopping distance = thinking distance + braking distance', what units is stopping distance measured in?

Answer 43

Like all distances, stopping distance is measured in metres (m)

Question 44

In the equation K.E. = ½mv² | what does 'K.E.' stand for, and what units is it measured in?

Answer 44

'K.E.' stands for 'Kinetic Energy'. Like all energies, it is measured in Joules. (J)

Question 45

In the equation F = kx | what does the 'x' stand for, and what units is it measured in?

Answer 45

Here 'x' stands for extension. Since extensions are distances, it is measured in metres. (m)

Question 46

In the equation G.P.E. = mgh | what does 'g' stand for, and what units is it measured in?

Answer 46

Here 'g' stands for gravitational field strength. Its units are N/kg.

Question 47

In the equation P₁V₁ = P₂V₂ | what does the 'P₂' stand for, and what units is it measured in?

Answer 47

P₂stands for 'final pressure'. It is measured in Pascals. (Pa)

Question 48

In the equation Q = It | what does the 't' stand for, and what units is it measured in?

Answer 48

Here 't' stands for 'time'. It is measured in seconds. (t)

Question 49

In the equation V = IR | what does the 'I' stand for, and what units is it measured in?

Answer 49

Here 'I' stands for 'current'. It is measured in amps. (A)

Question 50

In the equation v = fλ | what does the 'λ' stand for, and what units is it measured in?

Answer 50

Here 'λ' stands for wavelength. Like all distances, wavelength is measured in metres. (m)

Question 51

In the equation n = sin(i) ÷ sin (r) | what does the 'r' stand for, and what units is it measured in?

Answer 51

Here 'r' stands for angle of *refraction*. (measured in degrees) Don't confuse this with the law of reflection, which is 'angle of incidence = angle of *reflection*

Question 52

In the equation P = ρgh | what does the 'ρ' stand for, and what units is it measured in?

Answer 52

Here 'ρ' stands for density, measured in kg/m³.