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While traveling on a horizontal road at speed vi, a driver sees a large rabbit ahead and slams on the brakes. The wheels lock and the car be
Question
While traveling on a horizontal road at speed vi, a driver sees a large rabbit ahead and slams on the brakes. The wheels lock and the car begins to slide against the road. The car collides with the rabbit at a final speed of vf, after T seconds of braking. What is the coefficient of kinetic friction of the tires against the road?
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Physics
3 years
2021-08-19T08:02:44+00:00
2021-08-19T08:02:44+00:00 1 Answers
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Answer:
μk = (Vf – Vc)/(T×g)
Explanation:
Given
Vi = initial velocity of the car
Vf = final velocity of the car
T = Time of application of brakes
g = acceleration due to gravity (known constant)
Let the mass of the car be Mc
Assuming only kinetic frictional force acts on the car as the driver applies the brakes,
The n from Newtown’s second law of motion.
Fk = Mc×a
Fk = μk×Mc×g
a = (Vf – Vc)/T
Equating both preceding equation.
μk×Mc×g = Mc × (Vf – Vc)/T
Mc cancels out.
μk = (Vf – Vc)/(T×g)