Question

The left side of the figure shows a light ('massless') spring of length 0.250 m in its relaxed position. It is compressed to 75.0 percent of its relaxed length, and a mass M=0.250 kg is placed on top and released from rest (shown on the right). The mass then travels vertically and it takes 1.50 s for the mass to reach the top of its trajectory. Calculate the spring constant, in N/m. (Use g=9.81 m/s2.)