Two blocks are connected to an ideal spring of stiffness

PHYSICS · Single correct · CBSE · Physics · Work, Energy and Power · Work, Energy and Power

Problem

200\,\mathrm{N\,m^{-1}}

. At a certain moment, the two blocks are moving in opposite directions with speeds

4\,\mathrm{m\,s^{-1}}

and

6\,\mathrm{m\,s^{-1}}

, and the instantaneous elongation of the spring is

10\,\mathrm{cm}

. The rate at which the spring energy

\left(\frac{kx^2}{2}\right)

is increasing is (1)

500\,\mathrm{J\,s^{-1}}

(2)

400\,\mathrm{J\,s^{-1}}

(3)

200\,\mathrm{J\,s^{-1}}

(4)

100\,\mathrm{J\,s^{-1}}