Question

A 2000 kg car has a speed of 23 mph at the top of a hill which is 144 m tall. How

fast will the car be going if it coasts to the bottom of the hill?

Answer 1

Answer:

Final speed, v = 54.64 m/s.

Explanation:

Given that,

Mass of a car, m = 2000 kg

Initial speed of the car, u = 23 mph = 10.28 m/s

height, h = 144 m

We need to find the speed of the car at the bottom of the hill. Let v is the speed. Applying conservation of energy as :

$\dfrac{1}{2}mu^2+mgh=\dfrac{1}{2}mv^2\\\\v^2-u^2=2ah$

a = g here

$v=\sqrt{2gh+u^2}\\\\v=\sqrt{2\times 10\times 144+(10.28)^2}\\\\v=54.64\ m/s$

So, the speed at the bottom of the hill is 54.64 m/s.