A spring gun shoots out a plastic ball at speed v0. If the ball's speed is increased by a factor of 2, what distance must the spring have been compressed?

Answer 1

Ke = (1/2)m v^2 = Pe = (1/2)k x^2

(1/2)m (2v)^2 = (1/2)k (nx)^2

v^2 multiplied by 4
so x^2 multiplied by 4
so 2 times original x