Newton's Third Law Action-Reaction Pair Requirements

Steps:

• Recall Newton's third law: For every action force, there is an equal and opposite reaction force.
• Identify core requirements: Forces must be equal in magnitude, opposite in direction, and act on two different objects.
• Evaluate choices against these: Check if each is always necessary for the law to apply.
• Determine the non-requirement: Select the option that does not match the law's definition.

Why B is correct:

• Newton's third law applies to all interacting forces, including non-contact ones like gravity or magnetism, not just those between objects in contact.

Why the others are wrong:

• A: The law explicitly states action and reaction forces are opposite.
• C: Action-reaction pairs always involve two different objects by definition.
• D: The law requires forces to be equal in magnitude.

Final answer: B