25. (a) how high a hill can a car coast up (engine disengaged) if work done by friction is negligible and its initial speed is 110 km/h? (b) if, in actuality, a 750-kg car with an initial speed of 110 km/h is observed to coast up a hill to a height 22.0 m above its starting point, how much thermal energy was generated by friction? (c) what is the average force of friction if the hill has a slope 2.5º above the horizontal?

a) 47.63 m

b) 188572.725 joule

c) 373.88 N

Explanation:

Given data:

initial speed  = 110 km/hr = 110,000 m/3600 s = 30.6 m/s

solving y_f we have

b) loss of energy = m g (47.63 - 22)

= 750(9.81)(25.63) = 188572.725 Joules lost

c)  work done = force acted in motion direction × distance moved

F = 373.88 N

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