A body of mass 2 kg starts from rest and moves in a uniform acceleration. It acquires a velocity of 20 ms^(-1) in 4 s. The power exerted on the body at 2 s in watt is

A body of mass 2 kg starts from rest and moves in a uniform accelerati

1.	A body of mass 2 kg starts from rest and moves in a uniform acceleration. It acquires a velocity of 20 ms^(-1) in 4 s. The power exerted on the body at 2 s in watt is
Answer» 50 100 150 200 SOLUTION :Here, `U = 0 , m = 2 kg` Let a be the uniform accelration. Using , `v = u + at` `:. 20= 0+ a(4) or a = (20)/4 = 5 ms^(-2)` Force , `F = ma = (2 kg)(5 ms^(-2)) = 10 N` The velocity acquired by the body in 2s is `v = at = (5 ms^(-2))(2s) = 10 ms^(-1)` Power exerted on the body is `P = Fv = (10 N)(10 ms^(-1)) = 100 W`.