newton's law of motion

Question

An ice skater pushes off a railing. Which of the following is the reaction force?

a) the force of gravity

b) the force of the skater pushing off the railing

c) the force of the railing pushing back on the skater

d) the force of fricition on the ice

Answer 1

Assuming the ice skater pushing off the railing is the force in question, the reaction force must be equal in magnitude (or value) and opposite in direction to this force. The reaction force would be the force of the railing pushing back on the skater. This force is opposite in direction, but will be the SAME amount of force as the skater pushes on the railing.

These two forces are commonly known as "Newton's 3rd law pairs".

Newton's third law states that every force has and equal and opposite reaction force. For example, I push on a book, the book pushes back on me. Gravity pulls me down on the earth, I pull up on the earth.