Examples of Inertia
Situation 1:
A heavy object moves horizontally towards the right side at a constant speed of 2 m/s. What is the net force required to keep the object moving at the same speed in the same direction?
The answer is zero. If there will be a net force acting on the object, then its velocity will change. An object will continue to move at a constant velocity unless acted upon by an unbalanced force.
Situation 2:
A tennis ball is thrown with great speed. Will it have more inertia because of the greater speed?
Inertia depends only on the mass of the object and nothing else. An object with greater mass will have greater inertia. The speed at which the ball is thrown has no relation with its inertia.
Situation 3:
Two bricks lying on a table are pushed. One brick moves 4 feet towards the right and the second brick moves 3 feet to the right. The brick that moves 3 feet has more inertia, right?
It may seem so, but, the correct answer is that the given information is not enough. There is a possibility that more force was applied on the first brick as compared to the second brick and that is why it displaced 4 feet towards the right.