Question

Which of the following has more inertia - A rubber ball or a stone of the same size?

Answer 1

Hint : The inertia of a body is a property of it that serves as a measure of the resistance that it offers to any change in its state of motion. The greater the inertia of the body, the greater is its tendency to remain in the same state of motion, that is, uniform motion or rest.

Complete step by step solution :
The inertia of a body is an inherent property of the body that is a measure of the body’s tendency to remain in the same state of motion or rest. A body with greater inertia has a greater tendency to resist any change in its motion. Hence, a greater external force has to be applied on the body to produce the same change in its state of motion than for a body with lower inertia.
The inertia of a body is seen to have a direct correlation with its mass. The greater the mass of the body, the greater is its inertia.
For a rubber ball and a stone of the same size, it is quite obvious that the stone has a greater mass since the density of the stone is much more than the density of rubber. Hence, since the stone has a greater mass, it also has a greater inertia.

Note : By solving this question, students must have gotten a feel why it is easy to kick a football made of rubber but very hard to kick a stone of the same size so that it goes the same distance. This is because the stone has a much larger mass, a much greater inertia and thus, much more tendency to remain in its state of rest.