Edexcel IGCSE Physics Forces and motion units questions

Forces and motion units syllabus

Questions on forces and motion units can test recall, calculations, explanations, diagrams, data handling and practical skills. You should be able to:

1.1 use the following units: kilogram (kg), metre (m), metre/second (m/s), metre/second² (m/s²), newton (N), second (s) and newton/kilogram (N/kg)
1.2P use the following units: newton metre (Nm), kilogram metre/second (kg m/s)

How to answer forces and motion units questions

Write the unit symbol exactly and distinguish quantities that use similar-looking units.
Convert prefixes and compound units before substituting values into an equation.
Check that the unit of the final answer matches the quantity asked for.
Use the context of a diagram or calculation to reject units with the wrong dimensions.

Forces and motion units example questions and worked answers

These examples show how information in a diagram, graph or experimental context becomes part of a complete exam answer.

Example 1: Converting a pipe measurement to centimetres

June 2016 · Paper 1P · Question 10(a)(iii)

Question 1

A student measures the diameter of a circular pipe using a digital calliper.

The calliper shows that the diameter is 15.10 mm.

Calculate the circumference of the pipe using the formula

circumference = diameter × π

Give your answer in centimetres.

calculated circumference = ________ cm

Final answer

The circumference of the pipe is 4.74 cm.

Mark scheme points

M1 Substitute the diameter in centimetres into circumference = diameter × π.
M2 Calculate the circumference: 4.744 cm, accepted as 4.74 cm or 4.7 cm. A correct answer without working earns both marks; a power-of-ten error can earn a maximum of one mark.

Explanation

The diameter is given in millimetres, but the circumference is required in centimetres. Convert the diameter first, then multiply by π.

15.10 mm = 1.510 cm
circumference = 1.510 × 3.142
              = 4.744 cm
              ≈ 4.74 cm

Common mistakes

Forgetting to convert the diameter from millimetres to centimetres before giving the circumference in centimetres.
Using the circumference formula correctly but omitting the final unit, cm.

Example 2: Matching physical quantities to units

June 2023 (R) · Paper 2P · Question 1(a)

Question 2

The boxes show some physical quantities and their units.

Draw a straight line from each physical quantity to its correct unit.

One has been done for you.

Matching diagram showing the physical quantities velocity, force, power, moment and acceleration, and the units metre per second squared (m/s²), watt (W), newton (N), metre per second (m/s) and newton metre (Nm); a line is already drawn from moment to newton metre (Nm).

Final answer

Draw the straight-line connections shown below.

Mark scheme points

M1–M3 Match all four remaining quantities correctly: velocity → m/s; power → W; moment → Nm; acceleration → m/s². All correct earns 3 marks; two correct earns 2 marks; one correct earns 1 mark.

The force → newton connection is already given and earns no additional mark. A connection is ignored if it links a quantity to more than one unit, or a unit to more than one quantity.

Explanation

Use these checks to remember the four matches:

Velocity: displacement divided by time gives metres per second, m/s.
Power: energy transferred per second is measured in watts, W.
Moment: force × perpendicular distance gives newton metres, Nm.
Acceleration: change in velocity divided by time gives (m/s)/s = m/s².

Common mistakes

Most candidates earned full marks. The most frequent errors involved acceleration and moment: check that acceleration uses m/s² and moment uses Nm.
Do not draw extra connections “just in case”. Each quantity must connect to exactly one unit.

Practise Forces and motion units questions

Build a focused practice set from this part of the Edexcel IGCSE Physics syllabus.

Generate Forces and motion units questions View the Forces and motion topic guide