Catapult Building 05/20/14

After a few trial runs the day before, we decided to do another one with the catapult completely done. After noticing that the dowel rod after it had been spray painted was causing trouble on the trigger, we took a clean piece and redid the trigger. We had to use a lubericant to make the friction between the dowel rod and arm decrease. After being happy with our catapult, we loaded it into the truck and took it home.

Catapult Building 05/19/14

After building the trigger and the sling, we decided to do some trial runs with our catapult. We put 15 pounds on each side for our counterweight and used normal water balloons for our payload. We had some trouble with our first trigger, so we tried an alternative, as shown below. Once we were okay with the distance, we decorated the catapult with red and white chevron strips and put our team name and our group member names on the side. After doing a few trials, we tried adjusting the sling to see if it would make a difference in distance.

Catapult Building 05/14/14

Tenley, Kevin, and I met at my house around after school. We started building more of the catapult. We finished the base of the catapult and started putting together the dowel rod to hold up the arm. We had to measure the lengths correctly and also make sure that the holes in the arms were even. after testing the arm out with some weight, we realized that the base of the catapult needed more support, so we added some more wood to create support legs.

Physics Portion: Projectile Motion

The trebuchet causes the payload to be a projectile, which is an object that is in constant motion due to its own inertia. the projectile motion is influenced by the gravitational force pulling down the arm downward and lifting the arm up to release the payload. The payload is thrown in the air with the force of the sling, arm, and the kinetic energy of the weights falling to bring the arm up and follow through the projectile motion. the projectile will go its furthest when the force is applied at a 45 degree angle.

Physics Portion: Force

The trebuchet catapult contains parts such as the base, arm, counterweight, and payload. Each compontent has several different forces acting on it. The base of the catapult has a gravitational force pulling down, while the normal force from the ground acts against the gravitational force. The arm experiences an applied force from the weights while it is launching due to the gravitaional force pulling down the weights. For our trigger mechanosm, there is a static frictional force before we pull rubbing against the supporting arms of the catapult and then a kinetic fritional force one the trigger is pulled out. The weights are experiencing a gravitaional force pulling the weights downward and pulling the launching arm up. The payload has a fritional force when it is rubbing against the base of the catapult and then experiences an applied force from the gravitational force. The applied force from the payload over comes the frictional force and the gravitaional force allowing it to be shot into the air. Adding more weights up to a certain point will increase the distane of the payload. The counter weight should be one-hundered ties heavoer than the payload for maximum launching. Putting liquid graphite into the holes and the dowel rod will help the friction between the wood so make the trigger machanism go smoother.

Physics Portion: Energy

The trebuchet catapult is the most efficient and accurate because it can transfer the stored energy to the projectile. It provides consistency in the projectile due to the fact that the same amount of energy can be delivered every trial. The trebuchet works by using the energy of the falling counterweight, and for maximum launch speed, the counterweight must be heavier than the payload. But there is a certain weight that the counterweight must be to make it most affective. Having the counterweight on the shorter end of the arm allows the payload to reach a larger linear velocity which allows for the payload to have a higher launch velocity. When the trebuchet is ready to launch, the counterweight and payload experience potential energy and then once it is released, the counterweight is influenced by the downward gravitational force and the payloads potential energy is transferred to kinetic energy.

Catapult Building 05/07/14

Tenley, Kevin, and I started construction of our catapult. We first sketched out a rough draft of what the catapult would look like and then according to the specifications of the guidelines we cut the wood to their lengths.