AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
Acceleration: The following equation applies to uniform acceleration:
Uniform acceleration means the velocity changes by the same amount each second, so acceleration is constant.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 1 of 23
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Uniform acceleration means the velocity changes by the same amount each second, so acceleration is constant. The equation that applies is v² − u² = 2as, where v is final velocity in m/s, u is initial velocity in m/s, a is acceleration in m/s² and s is distance in m. It links motion quantities without needing time. For example, a car accelerating uniformly from rest at 2 m/s² over 25 m reaches v² = 0² + 2 × 2 × 25 = 100, so v = 10 m/s. The equation applies only when acceleration is uniform and motion is in a straight line. It is used to find v, u, a or s when time is not given.
What earns the marks
- State that uniform acceleration means a constant rate of change of velocity, so the value of a stays the same throughout the motion.
- Identify the symbols correctly: v is final velocity, u is initial velocity, a is acceleration and s is distance travelled.
- Use the equation v² − u² = 2as, substituting values with consistent SI units before calculating.
- Recognise that the equation applies to straight-line motion with uniform acceleration, not to changing acceleration.
- Rearrange the equation correctly when finding u, a or s, including taking a square root when finding v or u.
Common mistakes and how to put them right
Treating u as acceleration or a as distance.
Put it right by writing a key beside each symbol before substitution.
Forgetting to square the velocities.
Put it right by squaring u and v before subtracting.
Using the equation when acceleration is not uniform.
Put it right by checking that the acceleration is constant before choosing this equation.
Exam tips
- Write the equation, then substitute values with units before doing arithmetic to reduce substitution errors.
- Check that all quantities are in SI units such as m/s, m/s² and m before calculating.
- If the answer requires velocity, remember to take the square root of v² and give the positive value for speed.
Try the lesson
The start of the Acceleration: The following equation applies to uniform acceleration: lesson, made from checked teaching notes for this specification point.
Have a go first
A cyclist slows uniformly from 15 m/s to 5 m/s in 5 s. Using a = (v − u) ÷ t, what is the acceleration?
Listen
Uniform acceleration means the velocity changes by the same amount each second, so acceleration is constant. The equation that applies is v² − u² = 2as, where v is final velocity in m/s, u is initial velocity in m/s, a is acceleration in m/s² and s is distance in m. It links motion quantities without needing time. For example, a car accelerating uniformly from rest at 2 m/s² over 25 m reaches v² = 0² + 2 × 2 × 25 = 100, so v = 10 m/s. The equation applies only when acceleration is uniform and motion is in a straight line. It is used to find v, u, a or s when time is not given. A strong answer earns marks for these points. State that uniform acceleration means a constant rate of change of velocity, so the value of a stays the same throughout the motion. Identify the symbols correctly: v is final velocity, u is initial velocity, a is acceleration and s is distance travelled. Use the equation v² − u² = 2as, substituting values with consistent SI units before calculating. Recognise that the equation applies to straight-line motion with uniform acceleration, not to changing acceleration. A common slip: Treating u as acceleration or a as distance. Instead, writing a key beside each symbol before substitution. Exam tip: Write the equation, then substitute values with units before doing arithmetic to reduce substitution errors.
See it
Key words
Say what each word means before you turn the card.
Uniform acceleration
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Equation linking motion quantities without time
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SI units and substitution
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See every definition
- Uniform acceleration
- Acceleration that is constant, so the velocity changes by the same amount each second.
- Equation linking motion quantities without time
- v² − u² = 2as, where v is final velocity in m/s, u is initial velocity in m/s, a is acceleration in m/s² and s is distance in m.
- SI units and substitution
- Values are substituted with consistent SI units before calculating, such as m/s, m/s² and m.
Label the diagram
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1Box 1
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3Box 3
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