1. Velocity and acceleration

2. What is velocity?
We say that velocity is the speed in a given direction
A roller coaster could be moving with constant speed around a track but as the direction of movement will change, the velocity won’t be constant.

3. Velocity
Two moving objects can have the same speed but different velocities
Imagine two cars travelling on the motorway. They are on opposite carriageways but both moving at 67m/h (30 m/s)
They pass each other
How far apart will they be 5
seconds after they pass
each other?

4. Acceleration
To be a sprinter you have to pick up speed quickly. This change in velocity is called acceleration
Acceleration is change in velocity per second
The unit of acceleration is m/s2
This means metres per second per second

5. Quite often we measure acceleration from standing or a low speed
Gravity causes things to accelerate towards the surface of the Earth at a rate of 10m/s2
It is possible to calculate the acceleration
Acceleration a = v−𝑢 𝑡

6. Acceleration a = v−𝑢 𝑡
v = final velocity in m/s
u = initial velocity in m/s
t = time taken in seconds
Mr Butler races his TA at the traffic lights on his way home. He goes from 0 m/s to 30 m/s when the lights change in 5 s. What is his acceleration?

7. Deceleration
Deceleration is when something slows down. It is negative acceleration.

8. Exam questions