Newton's Third Law of Motion – Long Answer Questions

Medium Level (Application & Explanation)

Answer:

Newton’s Third Law says: for every action, there is an equal and opposite reaction.
When you push your foot backward on the ground, that is the action force.
The ground pushes your foot forward with an equal and opposite reaction force.
This forward push from the ground makes you accelerate and move ahead.
The two forces are equal and opposite, but they act on different objects (foot and ground).
So they do not cancel each other, and you can walk forward.

Answer:

Action and reaction forces act on different objects, not on the same object.
When you push a wall, your hand applies an action force on the wall.
The wall applies an equal and opposite reaction force on your hand.
Your hand can feel this as pressure or even pain if you push hard.
These forces act on two different bodies, so they do not cancel on one body.
The wall stays still because other factors like its support and friction balance the forces on it.

Answer:

The rocket engine pushes hot gases downward at high speed.
The gases push the rocket upward with an equal and opposite reaction force.
This upward push is called thrust.
The forces are equal in size and opposite in direction.
The rocket does not need air to push against; it works even in a vacuum.
The push comes from the interaction between the rocket and its exhaust gases.

Answer:

The swimmer’s hands and feet push water backward.
Water gives an equal and opposite reaction force on the swimmer’s body.
This reaction force pushes the swimmer forward.
Stronger strokes mean a larger action force on water.
So water gives a larger reaction force on the swimmer.
Hence the swimmer moves faster and covers more distance with each stroke.

Answer:

Air rushes out of the balloon in one direction.
This is the action force by the balloon on the air.
The escaping air pushes the balloon back with an equal and opposite reaction.
So the balloon flies in the opposite direction of the airflow.
The two forces act on different objects (air and balloon).
This is the same idea as a rocket’s thrust.

Answer:

When they push, the forces are equal and opposite by the Third Law.
Each student experiences the same force in magnitude.
But their accelerations are different because their masses are different.
The lighter student gets a larger acceleration for the same force.
So the lighter student moves faster and covers more distance.
The heavier student moves slower, even though the force is equal.

Answer:

The Earth pulls the book downward; that is the book’s weight.
The book pulls the Earth upward with an equal and opposite gravitational force.
The table pushes the book upward with a normal reaction.
The book pushes the table downward with an equal and opposite force.
So the pairs are: Earth–book (gravity) and table–book (normal).
The book’s weight and the normal on the book are not an action–reaction pair because they act on the same object (the book).

Answer:

The horse pulls the cart forward; the cart pulls the horse backward with an equal force.
These are action–reaction forces, acting on different objects.
The horse also pushes the ground backward with its hooves.
The ground gives an equal and opposite forward reaction on the horse.
This forward push from the ground moves the horse and cart together.
Motion happens because the unbalanced force on the system comes from the ground’s reaction.

Answer:

To walk, your foot must push the ground backward.
The ground must give a forward reaction force to move you.
On smooth ice, friction is very low, so the reaction is too small.
Without enough forward reaction, you slip instead of moving.
Use shoes with rough soles or spikes to increase friction and reaction.
Walk with shorter steps and lower speed to reduce slipping and keep balance.

Answer:

The engine throws gases backward at higher speed.
The gases push the rocket forward with an equal and opposite reaction.
Faster exhaust means a stronger push on the gases each second.
So the rocket feels a stronger thrust forward.
The exact amount also depends on how much gas mass is expelled each second.
But with higher exhaust speed, thrust generally increases, so the rocket accelerates more.