Physics: February 2016

Egg Joust Project

Kristian Fadrigon, Ellis Sutton, Eric Alipio

Period 4

Physics

Mr. Yav

The Trapper

Table of Contents:

Introduction
Design
Construction Procedure
Operation of Mousetrap Car
Results
Conclusion/Improvements
Appendix

Introduction:

The purpose of this project is to demonstrate the property of conservation of energy, as it is transferred from elastic potential energy to kinetic energy. To demonstrate this, we must construct a mousetrap car that will travel a distance of 1.5 meters in the shortest amount of time. Additionally, the conservation of momentum will be observed as different groups’ cars come crashing together.

Design:

In coming up with the design of our mousetrap car, there were several variables that we had to take into account. These variables include the size and type of the wheels, the wheel-to-axle ratio, the weight of the car, and the length of the snapper arm that pulls the string. In our initial brainstorming session, we opted for a decently-sized body with a smaller wheels and a longer snapper arm, which would also be used as a weapon for the joust portion of the project. We were also thinking of using a ramp to alter the direction of the opposing vehicles, but we decided to use a piece of cardboard and attach it to the end of the snapper arm that acted as a shield from the opposition's offensives. We chose small wheels because that allowed more rotations and thus a faster speed. The wheels we chose were rubber KNEX wheels that had a lot of friction, resulting in greater power and spin efficiency. We also decided to use a long snapper arm so that it disperses energy it one smooth, long pull, allowing for a greater distance. The body itself was constructed out of wood, which made our vehicle somewhat heavier than what is ideal, but we thought that we could balance out the weight by optimizing the conditions for the other variables, such as the snapper arm length and the size and type of the wheels. The following materials were used in the construction (bold indicates the item was found at home and its estimated price is listed):

Material	Price	Name
Mousetrap	$1.98	Kristian
Wood	$6.00	Ellis
Snapper Arm	$.50	Kristian
Wheels	$2.00	Eric
Axle	$3.99	Ellis
String	$3.99	Eric
Adhesive	$4.00	Eric/Kristian
TOTAL PRICE: TOTAL SAVINGS:	$9.96 ($22.46 total) $12.50

Construction Procedure:

To begin, we cut out 3 pieces of plywood. The first piece (the main body) is a by 10 cm large cut out. The 2 other pieces (the sides) are identical that have the dimensions of 25 by 3 cm.

Secondly, we nailed each side piece to the long sides of the main body.

Before we secure the mousetrap to the car, we removed all pieces that were not the spring or the lever.

After, we nailed the mousetrap all the way back and to the right side of the body.

Next, we duct taped a long, skinny rod to the lever in order to lengthen the pulling of the string.

3 inches from the tip of the rod, we taped a small cardboard cut out on to the rod as a shield.

And then, we drilled 4 holes equidistant on the front and backside of the side pieces.

We placed 2 skewers through the holes and capped each side of the skewers with our 4 KNEX car wheels.

Lastly, we attached the lever of the mousetrap to the back skewer with a long piece of string.

Operation of Mousetrap Car:

Our mousetrap car works by the lever pulling the string which pulls the back skewer (the axle) and its wheels. Since our lever was extended by a long rod, the length at which the string is pulled is also extended, increasing the overall distance our car could achieve. When we pulled back the lever, potential energy was created. Once we let go of the lever, kinetic energy was released. Similarly, our 4 inch in diameter front wheels allow them to have more rotation and thus more speed than our back wheels. Our back wheels, being 6 inches in diameter, allowed our car to travel greater distances because it took longer rotations with less power needed. The big wheels in the front had more friction acting upon them as they had more surface area and more mass, causing our car not to travel as fast as possible. Since our car was made of wood and our parts were fairly bulky, we gained more momentum as our car moved because of its mass and increasing velocity. This allowed for a greater impact as it hit the other vehicles. To help minimize the change of momentum or impulse we added the shield which would dampen the impulse since the shield would bend slowing down the car.