A5.2 g marble is fired vertically upward using a spring gun. the spring must be compressed 8.0 cm if the marble is to just reach a target 13 m above the marble's position on the compressed spring.
(a) what is the change in the gravitational potential energy of the marble-earth system during the 13 m ascent?
j

(b) what is the change in the elastic potential energy of the spring during its launch of the marble?
j

(c) what is the spring constant of the spring?
n/m