Physicsmedium · Past Paper
A car moving at 20 m/s comes to rest in 5s after applying brakes. The retardation is:
A4 m/s^2
B-4 m/s^2
C100 m/s^2
D5 m/s^2
✓ Correct Answer: A — 4 m/s^2
a = (0 - 20) / 5 = -4 m/s^2. Retardation is the magnitude of negative acceleration, which is 4 m/s^2.
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