(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 of 2.5º above the horizontal?

Explanation:

a ) Let the height achieved be h .

We shall apply law  of conservation of mechanical energy.

1 /2 mv² = mgh

h = v² / 2g

v = 110 km/h

= 30.55 m /s

h =

h = 47.61 m

b )

Kinetic energy of car in the beginning

= 1/2 x 750 x (30.55)²

= 349988.43 J

Potential energy at 22 m height

= 750 x 9.8 x 22

= 161700 J

Energy lost due to frictional force

= 349988.43 - 161700

= 188288.43 J

c )

Distance covered along the slope

d = 22 / sin2.5

= 22 / 0.043619

d = 504.36 m

If F be average frictional force

work done by friction

F x d

= F x 504.36

so

F x 504.36 = 188288.43

F = 188288.43 / 504.36

= 373.32 N

the answer is b, have negligible mass

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)