A block of mass \(m\) is moving with initial velocity \(u\) towards a stationary spring of stiffness constant \(k\) attached to the wall as shown in the figure. Maximum compression of the spring is:
(The friction between the block and the surface is negligible).
               
1.  \(u\sqrt{\frac{m}{k}}\)
2.  \(4u\sqrt{\frac{m}{k}}\)
3.  \(2u\sqrt{\frac{m}{k}}\)
4.  \(\frac12u\sqrt{\frac{k}{m}}\)