This PhysCast will analyse a motion problem using conservation of energy. A 1.25 kg ball is attached to the ground by a spring with k = 22 N/m and upstretched length of 0.55 m. The ball is thrown straight upwards, being released when it is 1.0 m above the ground, moving at 12.0 m/s. How fast is the ball moving when it is 2.0 m above the ground?