The potential energy of a certain spring when stretched through a distance 'S' is `10` joule. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance 'S' will be

Options

A. 30
B. 40
C. 10
D. 20

Answer

A

Explanation

`U_1=(1)/(2)ks^2=10`
`U_2=(1)/(2)k(s+s)^2=4xx(1)/(2)kx^2=40`
`W_(1rarr2)=U_2-U_1=30J`