Why are both reaching at the ground at the same time?

Hint: For any object which is free falling, the acceleration is caused by the acceleration due to gravity. The acceleration due to gravity acting on a body is constant and it is independent of any variables.

Complete step by step answer:
In the diagram, we can see that a man and an elephant are falling from top freely. It is given that both are reaching the ground at the same time. We are asked to find the reason for this.
We all know, for a free falling body the acceleration is caused by the acceleration due to gravity. This acceleration is due to the gravitational pull of earth so we call it acceleration due to gravity, it does not depend upon the test mass.

So, whatever the mass of two bodies, if it is dropped from the same height it will reach the ground at the same time with the same velocity and acceleration (provided the mass should not be affected by the air resistance).

This is the reason why the man and the elephant which are dropped from the same height reach the ground at same time even if the mass of the elephant is much higher than that of man.

Note: We know that velocity of an object changes only under the action of a force, here, the force is due to the gravity. Under the action of gravitational force, the body begins to accelerate toward the centre of earth. The value of acceleration due to gravity near the surface of the earth is, \[g = 9.8{\text{ }}m{s^{ - 2}}.\] The acceleration due to gravity depends on the mass and radius of the earth not on the mass of the object.