Which of the diagrams in figure, correctly shows the change in kinetic energy of an iron sphere falling freely in a lake having sufficient depth to impart if a terminal velocity ?

Options

A.
B.
C.
D.

Answer

B

Explanation

When an iron sphere falls freely in a lake, its motion is accelerated due to gravity and retarded due to viscous force. The overall effect is increase in velocity and hence increase in kinetic energy till the sphere acquire terminal velocity which is constant. Hence, kinetic energy of the sphere beyond this depth of lake becomes constant. Hence, option (b) represents the correct diagram.