A 1,200 kg car rolls down a hill with its brakes off and transmission in neutral. At one moment it is moving 5.0 m/s. A little later it is moving at 8.2 m/s. How much did its height change between the two times? Assume friction and air resistance have no effect on its motion.

Question

Physics

Lester

6 February, 04:15

A 1,200 kg car rolls down a hill with its brakes off and transmission in neutral. At one moment it is moving 5.0 m/s. A little later it is moving at 8.2 m/s. How much did its height change between the two times? Assume friction and air resistance have no effect on its motion.

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Karli Pacheco · Answer 1

The change in kinetic energy of the car is equivalent to the change in its potential energy. Thus:

K. E = P. E

1/2 x mΔv² = mgΔh

h = (8.2² - 5²) / 2 (9.81)

h = 2.15 meters