A force of 10 N acts on a body of mass 2 kg initially at rest. The momentum acquired by the body after 5 seconds is: MCQ with Answer and Explanation

A force of 10 N acts on a body of mass 2 kg initially at rest. The momentum acquired by the body after 5 seconds is:
A. 100 kg·m/s
B. 25 kg·m/s
C. 10 kg·m/s
D. 50 kg·m/s
Answer: Option D
Solution (By JKExamLibrary)
Force = rate of change of momentum: F = Δp/Δt. Thus Δp = F × Δt = 10 N × 5 s = 50 kg·m/s. Since initial momentum was zero (body at rest), final momentum = 50 kg·m/s. Alternatively, acceleration a = F/m = 10/2 = 5 m/s², velocity after 5s: v = u + at = 0 + 5×5 = 25 m/s, momentum p = mv = 2×25 = 50 kg·m/s. Both methods confirm. Memory tip: Impulse (FΔt) equals change in momentum. This direct application of Newton's second law is essential for dynamics problems in competitive exams.

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