Question

Two bodies of mass 1 kg and 5 kg are dropped gently from the top of a tower. At a point 50 cm from the ground then which quantity of the bodies will remain the same?
A. Momentum
B. Kinetic energy
C. Velocity
D. Total energy

Answer 1

Hint: Before going to solve this question we need to understand Gravity and gravitational force. Gravity exists everywhere in the universe and it is the most important force which affects all matter in space and also it is the weakest force. The force which acts between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres is known as gravitational force.

Complete step by step solution:
In order to understand this, let us consider two objects having different masses. When these two objects are made to fall from the top of the tower, we need to find which quantity will remain the same. We know that the momentum of an object is given by,
\[P = mv\]
Since the momentum depends on the mass and velocity of the body and two bodies possess different masses, the momentum cannot be the same.

Now, if we come to kinetic energy, we know that the formula for kinetic energy is,
\[K.E = \frac{1}{2}m{v^2}\]
In this equation, we can see that the kinetic energy is directly proportional to the mass of a body, and both bodies possess different masses, so kinetic energy is not the same.

If we consider the total energy, since the total energy of an object also depends on the mass of the object, the total energy is also not the same. The velocity of the bodies is the same because the gravitational acceleration on both of them possesses the same velocity and free fall under gravity is independent of the mass. Therefore, when the bodies of different masses fall from the same height only their velocity remains the same.

Hence, option C is the correct answer.

Note: Remember that the force of gravity always depends on the mass of the bodies and is inversely proportional to the square of the distance between their centres. When a body is made to fall from a height under the action of force is known as a free fall.