Mousetrap Car

Mousetrap Car!

Henry and I were able to create a car that moved 5 meters in 4.39 seconds!

His name was Thomas, a.k.a the little mousetrap car that could. Thomas was very frustrating and required a lot of tedious time. However, this only made it more satisfying when he crossed the finish line. In the end, we were able to connect the car to several physic's concepts. 
HERE ARE SOME PICS. 

The pictures above are some lovely self-portraits of Thomas himself!
If you take a look at the frame and body, you can see that it consists of a wooden board with a mousetrap car on top. We found that the smaller this was, the more likely it would accelerate. On the mousetrap car you can see the lever arm is a wooden stick with a string attached to the top. This connected it to the axle. The axle would overall would cause the car to move. This is important because there needed to be friction in between the axle and the stick. We found that by applying the sand paper to the stick, caused more friction to occur. Attached to the body are 4 CD's. It took us a while to figure out how to attach the wheels to the body and eventually we found that straws and a stick worked. The stick was placed inside the straw which allowed the wheels to actually move. On the wheels, we applied electrical tape which gave the wheels more friction. 

We were able to figure out how this related to physics- because it did in every way!

Newton's first law states that "An object in motion will stay in motion and an object at rest will stay at rest, unless acted upon by an outside force." In other words, the car in motion will continue to be in motion unless a force pushes it backwards. For Thomas, this force could derive from friction between the axle and the frame/ body.  This could be friction on the between the spring or friction between the wheels and the ground. However, we really only want friction between the wheels and the ground; if there was too much friction between the axel and the body, it would slow the car down. Finding a balance of too much friction and not enough was hard but we were able to do it by testing out many different methods. 

Newton's second law states that Acceleration = force/mass

Acceleration is directly proportional to force and inversely proportional to mass. 

 In the car, the force causes the acceleration. If there were too much mass, the car would not accelerate as much as it would with a tinier mass. In this way we wanted to construct a small body and frame to keep the mass small. 

A big force = big acceleration
too much mass = a little acceleration 

Newton's Third Law states that "Every action has an equal and opposite reaction. “In the case of the car, the action-reaction pairs were:

 -Car pushes ground back and ground pushes car forward. Because of the friction in the wheel, there is wheel torque. Remember that torque= force x lever arm. And if a wheel were bigger, it would have a bigger lever arm and therefor more torque. However, if it had a longer lever arm it would have too much rotational inertia. Therefor, it is important to find a balance. Our wheels were CDs and turned out to be the best size.

 The Law of Conservation of Energy states "the total amount of energy in a system remains constant (is conserved), although energy within the system can be changed from one form to another or transferred from one object to another. Energy cannot be created or destroyed, but it can be transformed."

Before the mousetrap is released, there is potential energy. Once it is released, it becomes kinetic energy (the energy of movement).

 Rotational velocity is the amount of rotations that object goes per unit time. On the car, the wheels have a rotational velocity. 
Big wheels = large rotational velocity
Small wheels = small rotational velocity

You have to find a balance in between.
Rotational inertia is an object's resistance to rotate. 
The bigger the wheels the bigger are, the more mass it has and then the more RI it has. 
The smaller the wheels are, the less mass there is and less RI. 
Tangential velocity is the linear speed of an object moving along a circular path. 
You want a large tangential velocity, which requires wheels moving at a fast pace. 

We can't calculate the speed of the car, potential energy, kinetic energy, or force exerted from the spring because it is constantly changing there is no work done because the force and distance are perpendicular. 

My partner and I originally designed a car in the shape of a triangle involving records and a CD. However, we soon recognized this to be a bad idea due to the mass aspect. We knew after watching some short clips on YouTube and reviewing Newton's second law that the mass had to be a lot smaller in order to accelerate. Like most people, we struggled finding the right methods to follow. However, we found that keeping the wheels the same size and keeping the mass as small as possible was the only way Thomas would move. We also struggled with the axle and how we would connect it. Through several trials, we found that the string needed to be short enough to come off the axle. I think really there was no major way of solving these tiny problems except for trying things out. Testing the big and the small led us to a good balance. Test runs got us to solve it. I think in the future, if we could redo it, Henry and I would probably be a bit more patient and probably be a bit more direct in planning it out. In order to make it faster though, we could make the mass smaller but maybe bigger wheels and create more friction in the wheels. I think that would get us a faster time. Overall, I think we did well on this project and we worked well together. Obviously, everyone struggled with finishing but I think we did a good job of not getting overly frustrated. 

And look at little Thomas go!