1. A mass of 7.2 kg is attached to the end of an un-stretched vertical spring and allowed to drop. The mass falls a distance of 10.2 cm before momentarily coming to rest. Find the spring constant.

2. The equation of motion for an object of mass 0.4 kg in SHM is given by

X = 9.2 cos(3.9t) (all SI units)

What is the velocity of the object as it passes through equilibrium?

3. A spring is vertically suspended. When a mass 0.36 kg is attached to the free end of the spring, the spring extends a length of 5.7 cm down to its equilibrium position. The mass is then pulled down a further 5.5 cm and released. Find the speed with which it passes through equilibrium.