An initially motionless test car is accelerated uniformly to 135 km/h in 8.18 se

Question

An initially motionless test car is accelerated uniformly to 135 km/h in 8.18 seconds before striking a simulated deer. The car is in contact with the faux fawn for 0.635 seconds, after which the car is measured to be traveling at 82.0kmh. What is the magnitude of the acceleration of the car before the collision? What is the magnitude of the average acceleration of the car during the collision? What is the magnitude of the average acceleration of the car during the entire test, from when the car first begins moving until the collision is over?

Explanation / Answer

a) Since the car is moving uniformly, acceleration of the car before the collision,

a = (v1 - v0)/t1 = [(135 - 0) * (1000 / 3600)] / 8.18 = 4.58 m/s2

b) Average acceleration during the collison,

aavg = (v2 - v1)/t2 = [(62 - 135) * (1000 / 3600)] / 0.635 = -31.9 m/s2

c) Average acceleration during the entire test,

aavg, entire = (v2 - v0)/(t1 + t2) = [(62 - 0) * (1000 / 3600)] / (8.18 + 0.635) =  1.95 m/s2

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