A raindrop falling from a height h above ground, attains a near terminal velocity when it has fallen through a height . Which of the diagrams shown in Figure correctly shows the change in kinetic and potential energy of the drop during its fall up to the ground?
The answer is the option (b)
At the height h, the raindrop will have zero kinetic energy and maximum potential energy. As it starts falling down, the PE starts decreasing, and the KE starts increasing proportionately. When we consider zero air resistance, the total mechanical energy remains conserved. However, if we consider air resistance, then there is an up-thrust which opposes the velocity of the droplet falling down, which makes the velocity constant as the time passes, which is known as terminal velocity. This relation is aptly depicted in graph b, and hence it is the correct option.