GCSE · Physics · AQA · Spec 8463
Acceleration (a = Δv/t)
Every rocket launch, emergency stop, and skydive is defined by one number: acceleration.
Physics · Terminal velocity
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Weight is greater than drag, so the resultant force is downward and the skydiver accelerates downward.
Switch between the two stages of the fall and compare the weight and drag arrows.
Relationship matrix
Tap any cell to reveal it. Tap a column header to read one property down every item.
Each cell hides a short answer and the reason behind it. Predict before you tap.
Calculate an acceleration
Problem
A train speeds up uniformly from 8 m/s to 32 m/s in 12 s. Find its acceleration.
AQA 2025–2027: a = (v − u)/t is printed on the full physics equation sheet provided with the papers. Its enduring specification classification remains recall-and-apply.
Predict, then check
Think about what the minus sign in an acceleration actually records.
A car is moving to the right, and we choose 'to the right' as the positive direction. The driver brakes and the car slows down. What best describes its acceleration?
When you know the distance, not the time
Problem
A car starts from rest (u = 0 m/s) and accelerates uniformly at 2 m/s² over a distance of 40 m. Find its final velocity.
AQA: v² − u² = 2as is an equation-sheet equation. For the 2025–2027 series it is included on the full physics equation sheet provided with the papers.
Check your answer against the model marking points
Model answers and marking points
Read each model answer and see which important points it includes.
Question
Explain why a skydiver reaches terminal velocity. (4 marks)
Student answer
As the skydiver falls, their speed increases. This means drag increases. The resultant force decreases because drag is getting closer to weight. When drag equals weight, the resultant force is zero, so acceleration is zero and the skydiver falls at a constant speed called terminal velocity.
Equations you need
Taken directly from the exam-board specification.
a = acceleration (m/s^2) · v = final velocity (m/s) · u = initial velocity (m/s) · t = time (s)
Learn it — you must recall this in the exam
v = final velocity (m/s) · u = initial velocity (m/s) · a = acceleration (m/s^2) · s = distance (m)
Given on the equation sheet — you must know how to use it
WHAT YOU'VE LEARNED
A quick recap of today's lesson.
What you need to know
- Acceleration is the rate of change of velocity: a = (v − u) / t.
- For uniform acceleration, v² − u² = 2as links initial velocity, final velocity, acceleration and distance.
- The sign of acceleration depends on the chosen positive direction. An object slows when its acceleration acts opposite to its velocity; if the direction of motion is chosen as positive, that deceleration has a negative value.
- Near Earth's surface, free-fall acceleration is about 9.8 m/s². Terminal velocity is reached when drag balances weight, so the resultant force and acceleration are zero.
- For AQA Physics, v² − u² = 2as is classified as an equation-sheet equation.
The big picture
Acceleration is the rate of change of velocity, so an object accelerates when its speed changes, its direction changes, or both. The sign of acceleration tells you its direction relative to the chosen positive direction; it does not, by itself, tell you whether the object is speeding up or slowing down. Near Earth's surface, free-fall acceleration is about 9.8 m/s². For an object falling through a fluid, drag grows until it balances weight; the resultant force and acceleration are then zero, so the object continues at constant terminal velocity.
Key points
Worked example
Problem
A motorbike reaches a velocity of 22 m/s after accelerating uniformly at 3.0 m/s² for 4.0 s. Calculate its initial velocity.
⚠ Watch out
Forgetting to subtract the initial velocity — if an object is already moving, you MUST use (v − u) in a = (v − u) / t, not just v. Using only the final velocity silently drops the 'change in' meaning.
★ Exam tip
If an AQA question gives initial velocity, final velocity and distance but no time, check whether v² − u² = 2as links the quantities you have before starting the calculation. This equation is classified as an equation-sheet equation.
Memory hook
Think of acceleration as a 'velocity-change meter': it tells you how quickly velocity changes. That can happen because speed changes, direction changes, or both — a sprinter speeding up and a car turning a corner are both changing velocity.
Check yourself
Take the object's initial direction of motion as positive. Without looking: its velocity changes from +25 m/s to +10 m/s in 5 s. What is its acceleration, and what does the sign tell you in this situation?
Flashcards
(14)What is acceleration?
What equation links acceleration, change in velocity and time?
A velocity changes uniformly from 8 m/s to 32 m/s in 12 s. What is the acceleration?
What does a negative acceleration tell you?
Forward is positive. A car slows uniformly from 20 m/s to 5 m/s in 3 s. What is its acceleration?
What is the approximate acceleration of free fall near Earth's surface?
When does an object falling through a fluid reach terminal velocity?
What are the acceleration and velocity doing at terminal velocity?
What equation links final velocity, initial velocity, acceleration and displacement for uniform acceleration?
An object starts from rest, reaches 8 m/s over 40 m and accelerates uniformly. What is its acceleration?
If velocity does not change over a time interval, what is the acceleration?
What is acceleration?
For AQA Physics, how is a = (v − u) / t classified, and what is different for the 2025–2027 exam series?
For AQA Physics, which equation in this lesson is classified as an equation-sheet equation in the specification?
Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.
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