Question

forces occur in pairs. if the first one is called the action force, the second would be the________. a. moving force b. resistance force c. reaction force d. normal force

Explanation:

According to Newton's third law of motion, forces occur in pairs. When one object exerts a force (action force) on another object, the second object exerts an equal and opposite force (reaction force) on the first object.

• Option A: "moving force" is not a standard term in the context of force pairs described by Newton's laws.
• Option B: "resistance force" is a more general term for a force that opposes motion but not specifically the paired force in the sense of Newton's third law.
• Option C: "reaction force" is the correct term as per Newton's third law when the first force is called the action force.
• Option D: "normal force" is a specific type of force (perpendicular to a surface) and not related to the force - pair concept in the way described in the question.

Answer:

C. reaction force