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A car is moving at 54 km/h at t = 0. The brakes are applied at t = 0, producing a constant retardation of 2.5 m/s² until the car stops. What is the displacement of the car (in metres) during the first 10 seconds after the brakes are applied?
- 45 m
- 90 m
- 75 m
- 50 m
Correct answer: 45 m
Solution
The car stops in 6 s (before the 10 s mark), so it travels only during the first 6 s. Displacement = 15*6 - (1/2)*2.5*36 = 90 - 45 = 45 m and remains 45 m at t = 10 s.
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