Momentum
Understand Momentum for GCSE Physics with this free worksheet and full mark scheme — Higher-tier exam-style questions with worked answers for AQA, Edexcel and OCR. A separate (triple) physics topic: momentum is the product of mass and velocity, p = mv, and is a vector quantity.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
This is a Higher tier only topic, so there's no Foundation paper — only the Higher worksheet and mark scheme below.
Topic overview
Momentum is a property of moving objects, defined as mass multiplied by velocity. This is a Triple-only and Higher-only topic.
The equation is momentum = mass × velocity, p = mv. Mass in kilograms, velocity in metres per second, and momentum in kilograms metres per second.
Momentum is a vector, because velocity is a vector. This means direction matters, and momentum in opposite directions has opposite signs. Two objects of equal mass moving towards each other at the same speed have momenta that are equal in size but opposite in sign, so the total momentum is zero.
Revision notes
The equation
Momentum = mass × velocity, p = mv.
Mass in kilograms, velocity in metres per second, momentum in kg m/s. A stationary object has zero momentum because its velocity is zero.
Momentum is a vector
Because velocity is a vector, momentum is also a vector with both magnitude and direction.
Momentum in one direction is taken as positive and momentum in the opposite direction as negative. This sign convention is essential when totalling momenta.
Comparing momenta
A large slow object can have the same momentum as a small fast one.
A 1000 kg car at 5 m/s has the same momentum as a 50 kg motorcycle at 100 m/s: both are 5000 kg m/s. Momentum depends on the product, not on either quantity alone.
Key points
- Momentum = mass × velocity.
- Momentum is measured in kg m/s.
- Momentum is a vector quantity.
- Direction matters, so signs are used.
- A stationary object has zero momentum.
- Mass and velocity together determine momentum.
Worked examples
Example 1
Calculate the momentum of a 1200 kg car travelling at 15 m/s. [2 marks]
Model answer
Momentum = mass × velocity = 1200 × 15 (1 mark) = 18 000 kg m/s (1 mark).
Example 2
Explain why momentum is a vector quantity. [2 marks]
Model answer
Momentum is calculated as mass multiplied by velocity (1 mark), and velocity is a vector with both magnitude and direction, so momentum has direction too (1 mark).
Example 3
A 0.5 kg ball moves at 8 m/s. Calculate its momentum. [2 marks]
Model answer
Momentum = mass × velocity = 0.5 × 8 (1 mark) = 4 kg m/s (1 mark).
Common mistakes
Giving momentum the unit of newtons.
Momentum is measured in kg m/s, not newtons.
Ignoring direction.
Momentum is a vector, so opposite directions take opposite signs.
Using speed instead of velocity.
Velocity includes direction, which matters for the sign.
Saying a stationary object has momentum.
Zero velocity means zero momentum.
Exam tips
- State kg m/s as the unit.
- Assign signs for direction before totalling momenta.
- Use velocity, not speed, in the equation.
- Remember this is Triple-only AND Higher-only.
Key terms
- Momentum
- Mass multiplied by velocity, in kg m/s.
- Vector
- A quantity with magnitude and direction.
- Velocity
- Speed in a given direction.
- Sign convention
- Assigning positive and negative to opposite directions.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.