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 : [tex]E_k=\dfrac{1}{2}mv^2[/tex]
As the rock was at rest initially, it means, its kinetic energy is equal to 0.
(b) The gravitational potential energy is given by : [tex]E_p=mgh[/tex]
It can be calculated as :
[tex]E_p=2.35\times 9.8\times 21.4\\\\E_p=492.84\ J[/tex]
(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.