A 6.76 kg block is attached to a spring with spring constant 36.9 N/m. While the block is sitting at rest, a student hits it with a hammer and almost instantaneously gives it a speed of 57 cm/s. What are

The amplitude of the subsequent oscillations?

The kinetic energy given by the blow, (1/2) M V^2, equals the spring potential energy at maximum deflection A:

(1/2) k A^2 = (1/2) M V^2

A = V*sqrt(M/k)

Make sure the V is in m/s