Last Updated on 2012-12-13

In this experiment, masses effect on efficiency of trebuchet (a catapult utilizing the force of a falling weight to hurl a projectile via a sling) were tested by comparing energy input to energy output.  Before the experiment commenced, the theoretical distance a projectile would travel was predicted based on 100 percent efficiency in transferring the counterweights potential energy to the projectiles kinetic energy.  Air resistance and friction were considered negligible in this experiment. This value was then compared to the actual distance the projectile goes and the actual efficiency was then calculated.  In each trial a different amount of mass (22.26, 24 and 26.2 kilograms) was added to the trebuchet’s counterweight, and five trials were given to each mass increase. As the counterweight mass increased, the distance traveled by the projectile (a ball) increased. The actual efficency of the trebuchet was extremely low, with an average of 8.9% among the three different counterweights.