Question

Newton's Third Law: Action & ReactionEvery time your cat’s paw hits her toy string, it swings away from her. How does this demonstrate Newton’s third law of motion?Objects with mass, such as your cat’s paw and toy string, will require inertia.Objects in action, such as the string toy, will experience force.For every motion from your cat’s paw, there is unbalanced inertia from the string.For every action your cat makes, there is an equal and opposite reaction from the strin

Answer 1

The correct statement that illustrates Newton’s Third Law is the last one (completed):
"For every action your cat makes, there is an equal and opposite reaction from the string."

Why that is correct (briefly):
- Newton’s Third Law says forces always come in pairs: if object A exerts a force on object B, then B exerts an equal-magnitude force in the opposite direction on A.
- When the cat’s paw pushes the string, the paw exerts a force on the string and the string simultaneously exerts an equal and opposite force on the paw. Those paired forces cause the string to accelerate (swing away) and provide a reaction felt by the paw.

Why the other statements are wrong or misleading:
- “Objects with mass ... will require inertia.” — Inertia is a property of mass (resistance to acceleration), but the wording “require inertia” is unclear and not a statement of the Third Law.
- “Objects in action ... will experience force.” — True in a vague sense, but not a description of action–reaction pairs.
- “For every motion from your cat’s paw, there is unbalanced inertia from the string.” — Misleading: inertia is not a force and does not “push back” as a separate agent. The correct idea is a force from the string on the paw (the reaction), not “unbalanced inertia.”

Extra useful note: the two forces act simultaneously and are equal in magnitude but opposite in direction. The resulting accelerations depend on each object’s mass (F = ma), which is why the light string moves a lot while the heavier paw hardly does.