Skip to content

Paper Together: sit a paper in a room with your friends.See how it works

Key ideas: units, vectors and equations: GCSE Combined Science Physics practice questions

Foundation and Higher · Grade 4

A second set of questions on key ideas: units, vectors and equations. They are different from the ones on the topic page. Try each, then open the answer and compare your working.

More questions

Question 1 Hard

Convert 0.35 A to milliamperes.

Show answer

Answer: 350 mA

  1. milli means one thousandth, so there are 1000 mA in 1 A.
  2. 0.35 × 1000 = 350 mA.

Question 2 Hard

A student walks 40 m north then 30 m south. State the distance and the displacement.

Show answer

Answer: distance 70 m, displacement 10 m north

  1. Distance = 40 + 30 = 70 m.
  2. Displacement = 40 − 30 = 10 m north.

Question 3 Hard

A potential difference of 12 V is across a resistor and the current is 0.40 A. Rearrange V = I × R for R and calculate it.

Show answer

Answer: 30 Ω

  1. R = V ÷ I.
  2. 12 ÷ 0.40 = 30 Ω.

Question 4 Hard

Write 0.0035 in standard form.

Show answer

Answer: 3.5 × 10⁻³

  1. The decimal point moves 3 places to give 3.5.
  2. A small number has a negative power.

Quick checks

Short questions with options. Choose one before you open the answer.

Check 1

What is the unit of force?

  1. the newton, N
  2. the joule, J
  3. the watt, W
Show answer

the newton, N Force is measured in newtons.

Check 2

What is the unit of energy?

  1. the newton, N
  2. the joule, J
  3. the watt, W
Show answer

the joule, J Energy is measured in joules.

Check 3

What is the unit of power?

  1. the joule, J
  2. the volt, V
  3. the watt, W
Show answer

the watt, W Power is measured in watts.

Check 4

What is the symbol and unit for potential difference?

  1. V, in volts
  2. I, in volts
  3. V, in amps
Show answer

V, in volts Potential difference is the voltage across a component.

Check 5

What does the prefix kilo mean?

  1. 100
  2. 1000
  3. 0.001
Show answer

1000 So 1 kg is 1000 g.

Check 6

What does the prefix milli mean?

  1. one thousand
  2. one millionth
  3. one thousandth
Show answer

one thousandth So 1 mA is 0.001 A.

Check 7

What does the prefix mega mean?

  1. one million
  2. one thousand
  3. one thousandth
Show answer

one million So 3 MJ is 3 000 000 J.

Check 8

How do you change grams to kilograms?

  1. multiply by 1000
  2. divide by 1000
  3. divide by 100
Show answer

divide by 1000 For example 450 g is 0.45 kg.

Check 9

How do you change minutes to seconds?

  1. divide by 60
  2. multiply by 100
  3. multiply by 60
Show answer

multiply by 60 For example 2 minutes is 120 s.

Check 10

Convert 450 mA to amps.

  1. 0.45 A
  2. 450 000 A
  3. 4.5 A
Show answer

0.45 A Divide milliamps by 1000 to get amps.

Check 11

What is standard form?

  1. a number written with all its zeros
  2. a number from 1 to 10 times a power of 10
  3. any number times a power of 10
Show answer

a number from 1 to 10 times a power of 10 The speed of light is 3.0 × 10⁸ m/s.

Check 12

Write 25 000 in standard form.

  1. 25 × 10³
  2. 2.5 × 10⁻⁴
  3. 2.5 × 10⁴
Show answer

2.5 × 10⁴ The decimal point moves 4 places, so the power is 4.

Check 13

What is a scalar quantity?

  1. a quantity with size only
  2. a quantity with size and direction
  3. a quantity with no unit
Show answer

a quantity with size only Distance, speed, mass and energy are scalars.

Check 14

What is a vector quantity?

  1. a quantity with size only
  2. a quantity with size and direction
  3. a quantity measured in newtons
Show answer

a quantity with size and direction Force, velocity and acceleration are vectors.

Check 15

Which of these is a vector: energy, force or temperature?

  1. energy
  2. temperature
  3. force
Show answer

force A force pushes or pulls in a particular direction.

Check 16

What is the difference between distance and displacement?

  1. path length, or straight line with direction
  2. they are exactly the same
  3. distance has a direction and displacement does not
Show answer

path length, or straight line with direction Distance is a scalar and displacement is a vector.

Check 17

A student walks 5 m east and then 5 m west. What is the displacement?

  1. 10 m
  2. 0 m
  3. 5 m
Show answer

0 m The finish is the same as the start.

Check 18

Which uses displacement: speed or velocity?

  1. speed
  2. neither of them
  3. velocity
Show answer

velocity Velocity = displacement ÷ time.

Check 19

How do you rearrange an equation?

  1. do the same to both sides
  2. change only the side you want
  3. swap the symbols around at random
Show answer

do the same to both sides It keeps the equation balanced.

Check 20

Rearrange V = I × R to make R the subject.

  1. R = V × I
  2. R = V ÷ I
  3. R = I ÷ V
Show answer

R = V ÷ I Divide both sides by I.

Check 21

Rearrange speed = distance ÷ time to find the time.

  1. time = distance × speed
  2. time = speed ÷ distance
  3. time = distance ÷ speed
Show answer

time = distance ÷ speed Multiply both sides by time, then divide both sides by speed.

Check 22

Round 0.04567 to 2 significant figures.

  1. 0.046
  2. 0.045
  3. 0.05
Show answer

0.046 Start counting at the first digit that is not zero.

Check 23

A cyclist is said to travel at 600 m/s. What should you do?

  1. nothing, bikes can go that fast
  2. check the working
  3. change the unit to km/s
Show answer

check the working A sensible check can catch a slip with units or the decimal point.

Check 24

Why must you convert to base units before using an equation?

  1. to make the numbers bigger
  2. because examiners prefer big numbers
  3. so the units fit together
Show answer

so the units fit together A speed in m/s needs a distance in m and a time in s.

Keep going with Key ideas: units, vectors and equations

Practise free

Start free

Yumio is not affiliated with, endorsed by or connected to AQA, Pearson Edexcel or any other exam board.

Next topicPractise free