# 5.6.11 Velocity-Time Graphs

### Gradient of a Velocity-Time Graph

• A velocity-time graph shows how the velocity of a moving object varies with time

This graph shows two objects moving with an increasing velocity

#### Acceleration on a Velocity-Time Graph

• Velocity-time graphs also show the following information:
• If the object is moving with a constant acceleration/deceleration
• The magnitude of the acceleration/deceleration
• A straight line represents constant acceleration
• The slope of the line represents the magnitude of acceleration
• A steep slope means large acceleration (or deceleration) – i.e. the object’s speed changes very quickly
• A gentle slope means small acceleration (or deceleration) – i.e. the object’s speed changes very gradually
• A flat line means the acceleration is zero – i.e. the object is moving with a constant velocity

This image shows how to interpret the slope of a velocity-time graph

#### Calculating the Gradient of a Velocity-Time Graph

• The acceleration of an object can be calculated from the gradient of a velocity-time graph

The acceleration of an object can be found by calculating the gradient of a velocity-time graph

#### Exam Tip

Use the entire line, where possible, to calculate the gradient. Examiners tend to award credit if they see a large gradient triangle used – so remember to draw ‘rise’ and ‘run’ lines directly on the graph itself!

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