The potential energy of a certain spring when streched by a distance x is 20J. The amount of work required to strech it through an additional distance x is:

Options

A. 60J
B. 40J
C. 20J
D. 10J

Answer

A

Explanation

P.E of the spring `=(1)/(2)kx^(2)=20J`
When x becomes 2x
New `P.E=(1)/(2)k(2x)^(2)`
`=(1)/(2)kx^(2)xx4`
`=20xx4=80J`
Work done = New P.E - Initial P.E
`=80-20`
`W=60J`