Question

What is the Galileo experiment about first law of motion?

Answer 1

Galileo's Experiment — We have seen that an unbalanced force is needed to accelerate a body. But for long people believed that a force is needed to maintain the uniform motion of an object, and if no force acts on the object, it would come to rest. Many things we see around us mislead people into believing this. Let us see one such case. Consider a ball moving on a horizontal table with some speed. Suppose we do not do anything to the ball, and just watch. We find that its speed decreases and it stops after some distance. It may appear that the ball is slowing down although no force is acting on it. However, this is not true. Although we have not applied any force on the ball, there are other agencies applying forces on it. The table exerts a force of friction on the ball, and it is this unbalanced force that is responsible for the slowing down of the ball. If the table is made smoother, the force of friction is reduced and the ball moves through a larger distance. Imagine a situation in which we get rid of friction completely. Then the ball will continue to move without slowing down till it reaches the edge of the table and drops off. It was Galileo for recognise that a body moves with uniform velocity if no force acts on it. Before Galileo, there was a general belief that a force is necessary to keep a body moving with uniform velocity. Galileo arrived at the correct conclusion through a series of experiments and reasonings.