A toy cannon uses a spring to project a 5.34-g soft rubber ball. The spring is originally compressed by 5.10 cm and has a force constant of 8.05 N/m. When the cannon is fired, the ball moves 15.3 cm through the horizontal barrel of the cannon, and the barrel exerts a constant friction force of 0.031 9 N on the ball. (a) With what speed does the projectile leave the barrel of the cannon

pe = weightxheight = 2000x1000=2,000,000joules

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.