# Physics Behind Catapults

Essay by   •  May 19, 2011  •  Essay  •  292 Words (2 Pages)  •  12,082 Views

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Physics Behind Catapults

Catapults are a lever-system, built to launch certain objects over very longs distances. There are many kinds of catapults: Weight-Based, Elastic-Based, Trebuchets, ect. Although these catapults use different materials, they all have and perform the same action: Turning potential energy into kinetic energy.

The weight-based catapult uses gravitational potential energy to launch its lever. Dropping a weight onto one side, or releasing a weight from the launching side, will create high gravitational potential energy due to: Mass X Freefall X Height. All of that energy will become kinetic energy making the catapult launch at far distances (Heavier weight = Farther distance)

Elastic-based catapults can be used with either springs, or rubber cords. By pressing the lever against the springs or rubber bands, the force would create elastic potential energy which uses ½ Spring constant X (Distance compressed/stretched)^2. The spring or band without any force on it is called its relaxed length. (The farther the spring/band is stretched = More elastic potential energy). When released from compression, the elastic potential energy will turn into kinetic energy launching the lever.

The lever of a catapult uses angular momentum, (Moment of inertia X angular speed) since all rotating objects has inertia. This shows that when a catapult decreases its moment of inertia, the angular speed increases, creating more kinetic force.

The lever of a catapult uses angular momentum, (Moment of inertia X angular speed) since all rotating objects has inertia. This shows that when a catapult decreases its moment of inertia, the angular speed increases, creating more kinetic force.The lever of a catapult uses angular momentum, (Moment of inertia X angular speed) since all rotating objects has inertia. This shows that when a catapult decreases its moment of inertia, the angular speed increases, creating more kinetic force.

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