Chapter 3, Problem 13STP

To determine

An example in which object velocity will not change even if force is applied.

To explain: The reason for no change in velocity of an object for the given situation.

Explanation of Solution

Introduction:

The variation in the velocity of the object occurs due to the force applied. The applied force acts along the motion of the object. The velocity of the object does not change and either the net force along the motion is zero or the force acts normal to the motion of the object.

The reaction force always acts normal to the motion of the object, so the reaction force does not change the velocity of the object. The velocity of the object does not change due to the reaction force because the net force, which is normal to the object becomes zero.

When a force is applied on the heavy stationary box, then it does not start to move because the friction force due to the static friction between the box and ground resists the movement. The net force acting on the box in stationary state remains zero and the speed of the box does not change.

Conclusion:

Thus, the reaction force does not change the velocity of the object because the net force becomes zero and reaction also acts normal to the motion of the object.