Question

Shishir was playing with a spring. He was compressing and releasing it. Suddenly he noticed that a ball when kept on a spring attains a certain height after it is compressed and released. In which of the following heights attained by the ball, Shishir has to spend maximum of his energy?

• A. 3 m
• B. 5 m
• C. 7 m
• D. 9 m

Answer 1

The correct option is D

9 m

Maximum energy spent by Shishir depends on the work done by him in compressing the spring which in turn is directly proportional to the height attained by the ball after the spring is released. The gravitational potential energy is expressed as $mass\times height\times accelerationduetogravity$ and it would be the maximum for 9 m. So, he has to do maximum work to compress the spring when the ball rises to 9 m.