Two boys were playing with a ball on a level ground. One of the boys throws the ball on to the third floor of the building which is at a height of 5 m from level ground and the other boy manages to throw on to the fourth floor which is at a height of 7 m from the level ground.
The ratio of the work done by both the boys is?
The ratio of work done by both the boys is the respective change in gravitational potential energies of the ball.
Let m be the mass of the ball and g be the acceleration due to gravity.
Taking the ground level as the reference, the gain in gravitational potential energy for the first throw is m×g×5.
For the second throw, the change in potential energy is m×g×7.
The ratio of the work done is equal to
m×g×5m×g×7=5 : 7