A pop-up toy has a mass of 0.020 kg and a spring constant of 150 N/m. A force is applied to the toy to compress the spring of 0.050 meter (see the following figure)

a. Calculate the potential energy stored in the compressed spring

b. The toy is activated and all the compressed spring's potential energy is converted to gravitational potential energy. Calculate the maximum vertical height to which the toy is propelled.