Question

According to the Newton’s Third Law of Motion, action and reaction are equal and
opposite. The resultant force is not zero because
A. They are at different times
B. They act on different bodies
C. Their lines of action are different
D. They act on the same body

Answer 1

Hint: According to the Newton’s third law of motion, whenever an object applied a force (action) on another object, it will exert an equal and opposite force (reaction) on the first object
and they always act in pairs.

Complete answer:
When a person pushes (applies a force) a box with his hand, in response to the applied force
the box will exert an equal and opposite reaction force. Since the action and reaction forces are
acting on the different body, so the forces will not cancel out and cannot balance each other.
Thus, the resultant force is not equal to zero.

The applied force (action force) and the force exerted by the object (reaction force) take place
at the same time and it requires two bodies for action and reaction phenomenon. So option (A)
and option (D) are incorrect.

Since the action and reaction are equal and opposite direction so the line of action of action
and the reaction is the same. Thus, option (C) is incorrect.

Thus, the resultant force is not zero because the action and reaction forces act on different
bodies and option (B) is correct.

Note: If the action force and reaction force acts on the same body, then the reaction force will
be zero and the body will never be accelerated motion and no reaction can occur in absence of
action.