Velocity-Time Graphs (AQA GCSE Physics): Revision Notes

5.6.11 Velocity-Time Graphs

Velocity-Time Graphs

The gradient of a line on a velocity-time graph represents acceleration:

• The gradient is the steepness of the line. It shows how quickly the velocity is changing. A steeper (sharper) gradient means greater acceleration.
• A negative gradient (a line sloping downwards) indicates deceleration, meaning the object is slowing down.
• A horizontal line means the velocity is constant, so the object is moving at a steady speed.
• If the line is at 0 velocity (on the x-axis), the object is stationary.

The area under the line on a velocity-time graph represents the distance travelled:

• For straight lines, you can calculate this area using geometry (e.g., rectangles or triangles).
• For a curved line, counting the squares under the curve is often the best method to estimate the distance.
• A curved line on the graph indicates that the acceleration is changing. The object's speed is not increasing or decreasing at a constant rate.

Average Speed