Question

If a long spring is stretched by 0.02 m, its potential energy is U. If the spring is stretched by 0.1 m, then its potential energy will be

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

Answer 1

Answer: (D)

25U

Answer 2

$U \propto x ^ { 2 }$ ⇒ $\frac { U _ { 2 } } { U _ { 1 } } = \left( \frac { x _ { 2 } } { x _ { 1 } } \right) ^ { 2 } = \left( \frac { 0.1 } { 0.02 } \right) ^ { 2 } = 25$∴$U _ { 2 } = 25 U$