Force of 4 N is applied on a body of mass 20 kg. The work done in `3^(rd)` second is 

Options

A. 3 joule
B. 2 joule
C. 4 joule
D. 1 joule

Answer

B

Explanation

`a = F/M = 4/20 = 1/5 m//s^2`
`S = 1/2 at^2 = 1/2 xx 1/5 xx 3 xx 3`
work done in 3 second = ` 4 xx 1/2 xx 1/5 xx 3 xx 3 = 18/5 ` Joule
Work done in 2 second = `4 xx 1/2 xx 1/5 xx 2 xx 2 = 8/5 `Joule
Work done in `3^(rd)` second = `18/5 - 8/5 = 10/5 = 2` Joule.