1.

A body of mass 5 kg has momentum of 10 kg m/s. When a force of 0.2 N is applied on it for 10 seconds. What is the change in its kinetic energy (1) 1.1 J(2) 2.2 J (3) 3.3 J (4) 4.4 J

Answer»

Answer is (4) 4.4 J

u = p/m = 10/5 = 2m/s, a = (0.2/5) m/s2.

ν = u + at = 2 + (0.2/5) x 10 = 2.4 m/s2.

∆K = (1/2) mν2 - 1/2 mu2 = (1/2) x 5 x (2.4)2 – (1/2) x 5 x 22 = 4.4 J 



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