A ball with a mass of #420 g# is projected vertically by a spring loaded contraption. The spring in the contraption has a spring constant of #21 (kg)/s^2# and was compressed by #6/5 m# when the ball was released. How high will the ball go?
Potential energy in spring when it’s in compressed state is
According to law of Conservation of Energy
Total energy stored in spring = Total energy gained by ball