Answers for Part A) 12.5s Part B) -2.29 m/s^2 Part C) 13.1s Two cars are traveli

Question

Answers for Part A) 12.5s Part B) -2.29 m/s^2 Part C) 13.1s Two cars are traveling along 30 m/sec. At the moment the cars are 40 m apart, the lead driver applies the brakes so that her car accelerates at -2.0 m/sec a) How long does it take for the lead car to stop? b) Assuming that the chasing car brakes at the same time as the lead car, what must be the chasing o 492 a straight line in the same direction, the lead car at 25m/sec and the other at ar's minimum negative acceleration so as not to hit the lead car? How long does it take for the chasing car to stop? c)

Explanation / Answer

Here ,

u1 = 25 m/s

u2 = 30 m/s

distance , d = 40 m

a1 = - 2 m/s^2

a) let the time taken is t

t = u1/a1

t = 25/(2) = 12.5 s

the time taken for lead car to stop is 12.5 s

b)

let the minimum negative acceleration is a2

25 * 12.5 - 0.5 * 2 * 12.5^2 + 40 = 30 * 12.5 + 0.5 * a2 * 12.5^2

solving for a2

a2 = -2.29 m/s^2

the minimum negative acceleration is -2.29 m/s^2

c)

time taken is t

t = 30/(2.29) s

t = 13 s

the time taken for car to stop is 13 s

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