Newton's third law states that 'action and reaction are equal and opposite'. The most accurate restatement is:
AAction precedes reaction by a small time delay
BForces on one body cancel each other in pairs
CForce on A by B is minus the force on B by A
DNet force on a two-body system is always zero
Answer & Solution
Correct answer: C. Force on A by B is minus the force on B by A
1. The third-law pair acts on different bodies (one on A, the other on B).
2. The two forces occur simultaneously — there is no cause-effect delay.
3. Mathematically: F_AB = − F_BA at the same instant.
4. Option (B) is wrong because action–reaction pairs act on different bodies and do NOT cancel on a single body.
5. Option (D) is wrong: external forces on the two-body system need not be zero.
_Source: NCERT Class 11 Physics Ch 4 "Laws of Motion", §4.6 Newton's Third Law, p. 56–57_
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