Question

A railroad passenger car pushes down on the railroad tracks with a force of 2 x 10^5
N. Which of the following is the reaction force?
(A) The railroad tracks push up the car with 2 x 10^5 N
(B) The car pushes down on the railroad tracks with 2 x 10^5 N
(C) The buoyant force pushes up on the car with 2 x 10^5 N
(D) The car pushes down on the Earth with 2 x 10^5 N​

Answer 1

Answer:

(A) is correct.

Explanation:

The railroad tracks push up the car with 2 x 10^5 N

Answer 2

The reaction force is (A) The railroad tracks push up the car with $2$×$10^{5}N$.

Reaction Force:

A reaction force contradicts or opposes any particular action force by working in the opposite direction.

For example, when a block slides on a surface, the frictional force opposite to the block's movement is the Reaction force.

Action-Reaction force is based on Newton's third law.

Newton's third law:

If one body exerts a force on another body, then the second body must exert a force that has equal magnitude and opposite direction back on the first object.

In the question, the car pushes down tracks with $2$×$10^{5}N$ (action force), so  the tracks in return push the car up with $2$×$10^{5}N$.

Hence, the reaction force is (A) The railroad tracks push up the car with $2$×$10^{5}N$.

(#SPJ3)