When a spring is stretched by 2 cm, it stores 100 J of energy. If it is further stretched by 2 cm, the stored energy will be increased by

Options

A. 100 J
B. 200 J
C. 300 J
D. 400 J

Answer

C

Explanation

`100=(1)/(2)kx^(2) " "` (given)
`W=(1)/(2)k(x_(2)^(2)-x_(1)^(2))=(1)/(2)k[(2x)^(2)-x^(2)]`
`= 3xx((1)/(2)kx^(2))=3xx100=300J`