GCSE Physics

Speed Time Graphs: Deceleration

You will already have learned about deceleration. We can also find this from speed-time graphs:

speed time graphs and decelerationThe red line shows a deceleration from 30 to 0 m/s in 10 s. The green line shows a slower deceleration from 10 to 0 m/s over 20 s.

As with accelerations, the gradient (or steepness) of the line indicates the deceleration.

For the red line this is found as follows:
gradient = -30 / 10 = -3 m/s/s

For the green line the gradient is -10 / 20 = -0.5 m/s/s.

Note that both gradients are negative (they slope downwards) so these are decelerations, not accelerations.

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