A 7,500 pound truck is traveling on the freeway at 65 miles per hour when the dr

Question

A 7,500 pound truck is traveling on the freeway at 65 miles per hour when the driver suddenly notices a moose standing on the road 200 feet straight ahead. If it takes the driver 0.4 s to apply the brakes, and the coefficient of friction between the tires and the road is 0.5: a. Can the driver avoid the moose without steering to one side? b. Where will the truck come to rest relative to the moose? c. If the driver must steer to one side, determine the speed of the truck as it passes the moose. Please show all work algebra/steps/equations Thanks!

Explanation / Answer

a) m =7500 x 0.4535 = 3401.25 kg
a = .5 x 3401.25 x 9.81 / 3401.25 = 4.9 m/s2

u = 65mi/h = 65 x 1.609 x 1000/3600 = 29.05 m/s

d = 200ft x 0.3048 = 60.96 m

t = 0.4sec

d = ut - at2 /2

l.h.s = 60.96

r.hs. = 29.05 x 0.4 - 4.9 x 0.42 /2 = 11.23

r.hs is less than l.hs

so , truck need more time to stop.

No.

b) v2 - u2 = 2as

0 - 29.052 = 2 x 4.9 x s

s = 86.1125m or 282.52 ft

c) speed at t = 0.4s

v = u + at

v = 29.05 - 0.4 x 4.9 = 27.09 m/s

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