Question

Please help ASAP. A 1550 kg car is initially at rest on level ground when the engine does 450 000 J of work on it. After the car reaches its top speed, the engine cuts out and the car begins to roll up a hill. If the car continues to roll until its velocity is zero, what final height will it reach?

Answer 1

Answer:

29.6 m

Explanation:

Work is change in KE, and at the bottom of the hill, the car only has KE. Therefore, the car's total mechanical energy (ME) at the bottom of the hill must be equal to its KE (450 000 J). At the top of the hill, the car is no longer moving, so its total energy must be all gravitational potential energy. Following convervation of ME:

$ME_{i} = ME_{f}$

$KE_{i} = GPE_{f}$

$450 000 J = mgh_{f}$

$h_{f} = \frac{450 000 J}{m * g}$

$h_{f} = \frac{450 000 J}{1550 kg * 9.81 m/s^{2} } = 29.6 m$