The velocity of a body of mass 10 kg increases from 4 m/s to 8 m/s when a force acts on it for 2 s.

(a) What is the momentum before the forces acts?


(b) What is the momentum after the force acts?


(c) What is the gain in momentum per second?


(d) What is the value of the force?

Mass of the body, m = 10 kg

Initial velocity, u = 4 m/s


Final velocity, v = 8 m/s


Time, t = 2s


(a) Initial Momentum, p1 = mu


= 10 × 4 = 40 kg m/s


(b) Final Momentum, p2 = mv


= 10× 8= 80 kg m/s


(c) Gain in momentum for 2s = p2 – p1 = 40kg m/s


Gain in momentum per second = = 20kg m/s


(d) Acceleration, a = = = 2 m/s2


Force = m * a = 10 * 2 = 20N


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