A car is away from a traffic signal and is moving towards it at

PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A car is 30 m30\,\text{m} away from a traffic signal and is moving towards it at 20 m s−120\,\text{m}\,\text{s}^{-1}. The driver applies the brakes so that the car comes to rest exactly at the signal. After waiting for 5 s5\,\text{s} at rest, the car accelerates uniformly at 2 m s−22\,\text{m}\,\text{s}^{-2} for 10 s10\,\text{s}. (i) Calculate the magnitude of the uniform deceleration required to stop the car at the signal. (ii) How far from the original point of application of brakes is the car after completing the 10 s10\,\text{s} of acceleration?

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