There are many types of spring. Important among these are helical and spiral springs as shown in figure.
(a)
(b)
Usually, we assume that the springs are massless. Therefore, work done is stored in the spring in the form of elastic potential energy of the spring. Thus, potential energy of a spring is the energy associated with the state of compression or expansion of an elastic spring.
The potential energy of a spring increases by `15 J` when stretched by 3 cm. If it is stretched by 4 cm, the increase in potential energy is
Options:
(a) `27 J`
(b) `30J`
(c) `33 J`
(d) `36J`