A block of mass 10 kg , moving in x direction with a constant speed of 10 m s - 1 , is subjected to a retarding force F = ( 0 .1 ) x J m - 1 during its travel from x = 20 m to 30 m . Its final kinetic energy will be:

Question

A block of mass 10 kg , moving in x direction with a constant speed of 10 m s - 1 , is subjected to a retarding force F = ( 0 .1 ) x J m - 1 during its travel from x = 20 m to 30 m . Its final kinetic energy will be:, 475 J, 450 J, 275 J, 250 J

MARKS App · Accepted Answer

m = 10 k g , u = 10 m s - 1 Final KE will be given by K E f = K E i + W = 1 2 m u 2 + ∫ 20 30 - 0 .1 x d x = 1 2 × 10 × 100 + - 0.1 x 2 2 20 30 = 500 + - 0.1 2 900 - 400 K E f = 500 + - 0.1 500 2 = 475 J

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