What mistakes do students make with Momentum is a property of moving objects?

Using speed instead of velocity. Treat momentum as a vector and include its direction when required (HT only). Mixing units, such as using mass in grams. Convert mass to kilograms before calculating momentum (HT only). Omitting the units of momentum. Memorise and append kg m/s to all final answers, as it is often required for a mark (HT only).

What are the exam tips for Momentum is a property of moving objects in Combined Science AQA GCSE?

Write the equation p = mv, substitute values with units, then state the unit kg m/s in your answer (HT only). Include the direction of momentum whenever the question gives velocities along a specific line (HT only).

AQA · GCSE · Combined Science

Course version: 8464 · Version from Sept 2018

Momentum is defined by the equation:

Full specification wording

Momentum is a property of moving objects: Momentum is defined by the equation:

Momentum is a vector property of a moving object, defined by the equation p = mv, where p is momentum in kilogram metres per second (kg m/s), m is mass in kilograms (kg) and v is velocity in…

Checked against the AQA 8464 specification (opens in a new tab) on 20 September 2026.

Point 1 of 6
2 key terms

Study notes

From the checked teaching notes for this specification point.

The idea

What earns the marks

State the defining equation p = mv and identify each symbol correctly (HT only).
Use the correct unit, kg m/s, and recognise that momentum is a vector quantity (HT only).
Calculate momentum by multiplying mass in kilograms by velocity in metres per second (HT only).
Explain that a stationary object has zero momentum because its velocity is zero (HT only).

Common mistakes and how to put them right

Using speed instead of velocity.
Put it right: Treat momentum as a vector and include its direction when required (HT only).
Mixing units, such as using mass in grams.
Put it right: Convert mass to kilograms before calculating momentum (HT only).
Omitting the units of momentum.
Put it right: Memorise and append kg m/s to all final answers, as it is often required for a mark (HT only).

Exam tips

Write the equation p = mv, substitute values with units, then state the unit kg m/s in your answer (HT only).
Include the direction of momentum whenever the question gives velocities along a specific line (HT only).

Try the lesson

The start of the Momentum is a property of moving objects: Momentum is defined by the equation: lesson, made from checked teaching notes for this specification point.

Have a go first

A cyclist of mass 70 kg rides at a velocity of 5 m/s. Using the equation for momentum, what is the momentum of the cyclist?

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Listen

Momentum is a vector property of a moving object, defined by the equation p = mv, where p is momentum in kilogram metres per second (kg m/s), m is mass in kilograms (kg) and v is velocity in metres per second (m/s). Because velocity has direction, momentum also has direction. For example, a 1500 kg car travelling at 20 m/s east has a momentum of 30,000 kg m/s east. A stationary object has zero momentum. The equation shows that momentum increases with both mass and velocity. Note: Although the tier field states foundation and higher, all momentum content is strictly Higher Tier only (HT only) in the Combined Science specification. A strong answer earns marks for these points. State the defining equation p = mv and identify each symbol correctly (HT only). Use the correct unit, kg m/s, and recognise that momentum is a vector quantity (HT only). Calculate momentum by multiplying mass in kilograms by velocity in metres per second (HT only). Explain that a stationary object has zero momentum because its velocity is zero (HT only). A common slip: Using speed instead of velocity. Instead, Treat momentum as a vector and include its direction when required (HT only). Exam tip: Write the equation p = mv, substitute values with units, then state the unit kg m/s in your answer (HT only).

See it

It shows the momentum equation p = mv, what each symbol and unit means, and the consequences: momentum has direction, increases with mass and velocity, and is zero for a stationary object.

Key words

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Momentum

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Stationary object

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See every definition

Momentum: A vector property of a moving object, defined by the equation p = mv, where p is momentum in kilogram metres per second (kg m/s).
Stationary object: An object whose velocity is zero, so it has zero momentum.

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