Question

Show that walking of a man is an example of newton's third law of motion.

Answer 1

When a person walks on the ground, he/she pushes the ground beneath backwards at an angle. Thus the person exerts a contact force (push) on the ground. This is called the action force.

Then the ground (Earth) exerts an equal force on the foot of the person in the opposite direction. That is at an oblique angle. The vertical component of this reaction force enables the person to remain upright standing above Earth's surface. It cancels the weight of the person.


The horizontal component of the reaction force gives a forward acceleration to the person. So the person is able to move forward.


Thus walking is a good example of Newton's third law: for every action there is an equal and opposite force.

Answer 2

When we walk, our feet exert force on the earth or ground. This force is balanced by the gravitational force or pull of earth.

If these forces doesn't exist we may fall outward of earth. Here, Force exerted by our feet is action. Gravitational pull is reaction.


Hence there exists a action - reaction pair. These forces are opposite in direction and have equal magnitude.


Therefore, Walking on the road or some kind of surface is an example of Newton's third law which states that “ For every action, there exists equal and opposite reaction ”