Question

When a long spring is stretched by 2 cm, its potential energy is U. If the spring is stretched by 10 cm, the potential energy stored in it will be:

• A. $\frac {U}{5}$
• B. $5U$
• C. $10U$
• D. $25U$

Answer 1

Answer: (D)

$25U$

Answer 2

$U = \frac 12K(2)^2$
$U = 2K$
$U' = \frac 12K(10)^2$
$U' = 50K$
$U' = 25\ . \ 2K$
$U' = 25U$

So, thew correct option is (D): 25U