Question

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

• A. U/4
• B. 4U
• C. 8U
• D. 16U

Answer 1

Answer: (D)

16U

Answer 2

$U =\frac{1}{2} K (2)^{2}$ & $U '=\frac{1}{2} K (8)^{2}$
$\Rightarrow \frac{ U '}{ U }=\left(\frac{8}{2}\right)^{2}=16$
$\Rightarrow U'=16 U$