m = mass of pellet = 2.10 x 10⁻² kg
x = compression of spring at the time launch = 9.10 x 10⁻² m
h = height gained by the pellet above the initial position = 6.10 m
k = spring constant
using conservation of energy
spring potential energy = gravitational potential energy of pellet
(0.5) k x² = m g h
inserting the values
(0.5) k (9.10 x 10⁻²)² = (2.10 x 10⁻²) (9.8) (6.10)
k = 303.2 N/m
