Question

A vertical spring (ignore its mass), whose spring stiffness constant is 950 N m^-1

is attached to a table. The spring is compressed down 15 cm and a 300 g ball

placed on it. The spring is then released and the ball flied off vertically. Determine the initial speed of the ball

Answer 1

Apply conservation of energy:

$$\frac12 kx^2=\frac12mv^2,\\\space\\ v=x\sqrt\frac km=8.44\text{ m/s}.$$