Question

A 2.35-kg rock is released from rest at a height of 21.4 m. Ignore air resistance and determine (a) the kinetic energy at 21.4 m, (b) the gravitational potential energy at 21.4 m, (c) the total mechanical energy at 21.4 m, (d) the kinetic energy at 0 m, (e) the gravitational potential energy at 0 m, and (f) the total mechanical energy at 0 m.

Answer 1

Explanation:

Given that,

The mass of rock, m = 2.35-kg

It was released from rest at a height of 21.4 m.

(a) The kinetic energy is given by : $E_k=\dfrac{1}{2}mv^2$

As the rock was at rest initially, it means, its kinetic energy is equal to 0.

(b) The gravitational potential energy is given by : $E_p=mgh$

It can be calculated as :

$E_p=2.35\times 9.8\times 21.4\\\\E_p=492.84\ J$

(c) The mechanical energy is equal to the sum of kinetic and potential energy such that,

M = 0 J + 492.84 J

M = 492.84 J

Hence, this is the required solution.