Acceleration (Edexcel GCSE Physics): Revision Notes
Acceleration
Acceleration is the rate at which an object's velocity changes over time. It's measured in metres per second squared (m/s²). Whenever an object speeds up or slows down, it's accelerating.
- Acceleration shows how fast something is increasing or decreasing its speed.
You can calculate average acceleration with this formula:
Where:
- a is the acceleration in metres per second squared (m/s²),
- Δv the change in velocity in metres per second (m/s),
- t is the time taken in seconds (s).
- Δ (delta) means change, so Δv refers to the change in velocity.
You can also write this as:
Where:
- v is the final velocity,
- u is the initial velocity. By subtracting the starting velocity from the final velocity, you get the change in velocity.
Acceleration as a Vector
Acceleration is a vector quantity, which means it has both size (magnitude) and direction. If acceleration is negative, it means the object is slowing down (deceleration).
Uniform Acceleration
When an object has uniform acceleration, its velocity changes by the same amount during equal intervals of time. This means it's speeding up at a constant rate. If this is the case, you can use the following formula:
Where:
- v is the final velocity in metres per second (m/s),
- u is the initial velocity in metres per second (m/s),
- a is the acceleration in metres per second squared (m/s²),
- s is the distance in metres (m).
:::
This equation is useful when you don't know the time taken. If the object starts from rest, then its initial velocity u is 0.