The potential energy of a long spring when stretched by

The potential energy of a long spring when stretched by 2 cm is U. If the spring is stretched by 8 cm, the potential energy stored in it is

The potential energy of a spring =	1	kx²
	2

U =	1	k.(2)² = 4 ×	1	k
	2		2

For x = 8 cm,

Energy stored =	1	k.(8)² = 64 ×	1	k
	2		2

= 64 ×	U	= 16 U
	4