Acceleration and graphs of motion

Overview

Acceleration and its unit with a worked sprint start, deceleration, velocity–time graphs of a 100 m sprinter, gradients and areas, speed–time and velocity–time graphs, and using graphs to coach a sprinter.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is acceleration?

   Model answer

   Acceleration is the rate of change of velocity. Acceleration equals the change in velocity divided by the time taken.

2. 2

   What is the unit of acceleration?

   Model answer

   Acceleration is measured in metres per second squared (m s⁻²).

3. 3

   A sprinter goes from rest to 9 m s⁻¹ in 3 s. What is the average acceleration?

   Model answer

   The average acceleration is 3 m s⁻². The working is (9 − 0) m s⁻¹ ÷ 3 s = 3 m s⁻².

4. 4

   What is deceleration?

   Model answer

   Deceleration is a decrease in velocity over time. Deceleration is negative acceleration.

5. 5

   How is acceleration shown on a velocity–time graph?

   Model answer

   Acceleration is the gradient of a velocity–time graph. A steep upward line shows rapid acceleration.

6. 6

   Describe the velocity–time graph of a 100 m sprinter.

   Model answer

   The line rises steeply as the sprinter accelerates from the blocks. The line then levels off at maximum velocity and falls slightly near the finish.

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