Suppose a car approaches a hill and has an initial speed of

106

k

m

/

h

at the bottom of the hill. The driver takes her foot off the gas pedal and allows the car to coast up the hill.


A. If in actuality a

780

k

g

car with an initial speed of

106

k

m

/

h

is observed to coast up a hill and stops at a height

21.5

m

above its starting point, how much thermal energy was generated by friction in

J

?


B. What is the magnitude of the average force in newtons of friction if the hill has a slope of

27

∘

above the horizontal.