Question

The potential energy of a certain spring when stretched through a distance ‘S’ is 10 joule. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance ‘S’ will be

• A. 30
• B. 40
• C. 10
• D. 20

Answer 1

Answer: (A)

30

Answer 2

(given in the problem)

$\frac { 1 } { 2 } k \left[ ( 2 S ) ^ { 2 } - ( S ) ^ { 2 } \right] = 3 \times \frac { 1 } { 2 } k S ^ { 2 }$= 3 × 10 = 30 J