S4.8.2 For the adult
Velocity and acceleration
A bus leaves the stop and picks up speed. How do we say how quickly it speeds up?
What this chapter teaches
Acceleration is the change in velocity divided by the time taken, in m/s². On a velocity time graph the gradient is the acceleration and the area under the line is the distance while the velocity stays positive.
Three questions to ask
There is no one right wording. Listen for the idea.
- A car speeds up from 0 to 20 m/s in 8 s. How would you work out its acceleration?
- A car drives at a steady 30 m/s. What is its acceleration, and why?
- What does the area under a velocity time graph show, and when is it the distance?
After the chapter, the learner can
- Calculate acceleration from change in velocity and time
- Find acceleration and distance from a velocity and time graph
What they copy into their notebook
Acceleration = (v − u) ÷ t, in m/s². On a velocity time graph the gradient is the acceleration and the area is the distance, while velocity stays positive.