A spring gun is used to project a 0.5 kg ball, in order to perform this experiment the spring was initially

compressed by 0.005 m. Find the ball's speed when it leaves the gun, if the spring constant is 395 N/m.

Given that,

Mass of ball M = 0.5kg

Spring compressed x = 0.005m

Spring constant K = 395N/m

Speed of ball?

Using conservation of energy

Energy stored in the spring is equal to the kinetic energy of the ball

U = K. E

½kx² = ½mv²

½ * 395 * 0.005² = ½ * 0.5 * v²

4.9375 * 10^-3 = 0.25v²

v² = 4.9375*10^-3 / 0.25

v² = 0.01975

v = √0.01975

v = 0.14m/s