Answer:
The kinetic energy of the sliding block is =1/2×m×v
2
=1/2×4×2
2
=8 J
Now since there is no friction on the surface then it is a conservative system. So all the energy of the block will be transferred to the spring and will store as a potential energy. Suppose it will compress the spring by an amount of x m. So the potential energy of the spring will be =1/2×k×x
2
Equating there two energies and solving for x, we will get, 1/2×k×x
2
=8
Or 0.5(400)x
2
=8
⟹x=0.2 m.
Explanation: