Questions: Newton's Third Law: Action and Reaction
3 questions to test your understanding
Score: 0 / 3
Question 1 Multiple Choice
A swimmer pushes water backward with her hands. What is the reaction force?
AGravity pulling the swimmer down
BThe water pushing the swimmer forward
CThe swimmer pushing harder on the next stroke
DFriction from the pool floor
By Newton's Third Law, when the swimmer pushes water backward, the water pushes the swimmer forward with an equal and opposite force.
Question 2 True / False
When a small car collides with a large truck, the truck exerts more force on the car than the car exerts on the truck.
TTrue
FFalse
Answer: False
Newton's Third Law guarantees that the forces are equal in magnitude and opposite in direction, regardless of the objects' sizes. The car and truck experience the same force, but the car accelerates more because it has less mass.
Question 3 Short Answer
When you stand on the ground, you push Earth down with your weight. What is the reaction force?
Think about your answer, then reveal below.
Model answer: Earth pushes you upward with a force equal to your weight (the normal force).
By Newton's Third Law, if you exert a downward force on Earth, Earth exerts an equal upward force on you. This is the normal force that keeps you from falling through the ground.