Question

22-kg block of iron drops out of the back of pickup truck traveling at 55 mph. The block slides on

the road for 150 m before coming to rest.

(a) What is the coefficient of kinetic friction between the iron block and the road?

(b) By roughly how much has the temperature of the iron increased? Assume that it gets about

one-half of the thermal energy produced by its interaction with the road and assume that air

resistance is negligible.

Answer 1

Work done by friction is equal to change in kinetic energy as per work energy theorem. Using this we find the coefficient of kinetic friction as shown below. Half of the initial kinetic energy converts to heat energy. We use specific heat capacity of iron to find the required increase in temperature as shown below

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