A ball of mass 1.0kg is released from rest at a height of 20m above the ground. Neglect air resistance and answer the following.
a. (i) Calculate the speed of the ball when it is 10m above the ground.
b. (ii) Determine its speed just before it reaches the ground.
c. (iii) Find the ratio of its kinetic energy to its potential energy when it is 5m above the ground.