A ball bearing is held in a cup on the end of a pivoted rod. Weights can be added to the end of the rod opposite to that of the cup. The cup is pulled down and then released. The moving rod hits a stop and the ball bearing is projected out. When carrying out a pilot experiment, I found that increasing the weight on the end of the rod increased the distance travelled by the ball bearing. Also increasing the weight of the ball bearing decreased the distance. If you think of this as a simple pendulum, increasing the weight on the end of the rod should not affect the speed of rotation of the rod, and therefore not affect the distance that the ball bearing travels. The equation I am using to determine the distance travelled does not include the mass of the projectile, so there should be no effect when changing the mass of the ball bearing. Explain... Thankyou.