Which form of Newton's second law of motion is most general?
AF = m·a only
BF equals the change in energy
CF equals the change in displacement
DF equals the rate of change of momentum
Answer & Solution
Correct answer: D. F equals the rate of change of momentum
1. Newton's second law states that the rate of change of momentum equals the applied force.
2. In symbols, F = dp/dt.
3. When mass is constant, this reduces to F = m·a.
4. The momentum form covers cases where mass changes (e.g. rockets) as well.
5. So the general statement is that force equals the rate of change of momentum.
6. Options C and D conflate force with kinematic or energetic quantities.
_Source: Selina Concise Physics ICSE Class 9, Ch 3 'Laws of Motion' (aplustopper.com extract)_
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