Answer: The potential energy of the rock before it began to fall is 4900 J
Step-by-step explanation:
Force is defined as the mass multiplied by the acceleration of the object.

where,
F = force exerted on the object
m = mass of the object
g = acceleration due to gravity
Potential energy is defined as the energy possessed due to the height of the object.
Mathematically,

Or,

where,
= potential energy of the rock = ?
F = force applied on the rock = 98 N
h = height of the bridge from where the rock is thrown = 50 m
Putting values in above equation, we get:

Hence, the potential energy of the rock before it began to fall is 4900 J