Question

Now, conduct a thought experiment. We do a thought experiment when the conditions required for the experiment are difficult to recreate in the real world. Suppose, you find an object and a horizontal floor having such smooth surfaces that the force of friction between them is zero. Imagine, what will happen if you repeat steps 3 and 4 of Activity 6.1 with such an object and a horizontal floor? Will the velocity of the object decrease? Will the object ever come to rest or continue moving forever?

Answer 1

If the surface and the object were perfectly smooth and there were no friction, then once an object is pushed, it would keep moving with a constant velocity.

Its speed would not reduce because there is no opposing force acting on it. The object would never come to a stop on its own and would continue moving indefinitely at the same velocity unless some external force acts on it.

This clearly shows that friction is what causes moving objects to slow down and eventually stop in everyday life.