In figure, a block `A` of mass `2kg` is moving to the right with a speed `5m//s` on a horizontal frictionless surface. Another block `B` of mass `3kg` a massless spring of spring constant `222N//m` attached to it, is moving to the left on the same surface and with a speed `2m//s` . Let us take the direction to the right as the positive `X-` direction. At some instant, block `A` collides with the spring attached to block `B`. At some other instant , the spring has maximum compression and then, finally, blocks move with their final velocities. Assuming that `(i)` the spring force is conservative and so there is no conversion of kinetic energy to internal energy and `(ii)`, no sound is made when block `A` hits the spring, answer the following questions.

In the collision process, while the spring is getting compressed `:`

Options

A. both linear momentum and kinetic energy are conserved
B. both linear momentum and mechanical energy are conserved
C. linear momentum is conserved but mechanical energy is not conserved
D. Neither the linear momentum nor the mechanical energy remain conserved

Answer

B