A spring of spring constant `5 xx 10^(2) `Nm is streched initially by `5 cm` from the unstriched position . Then the work required to streach is further by another `5 cm` is

Options

A. `12.50 N-m`
B. `18.75 N-m`
C. `25.00 N-m`
D. `6.25 N-m`

Answer

B

Explanation

` k= 5 xx 10^(3) N//m`
`W = (1)/(2) k (x_(2)^(2) - x_(1)^(2) ) = (1)/(2) xx 5 xx 10^(3) [(0.1) - (0.05)^(2) ]`
`= (5000)/(2) xx 0.15 xx 0.05 = 18.75 N//m`