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| Final Mousetrap after successful trial |
Here is a picture of our final mousetrap car:
As you can see, I labeled all of the different parts of it to show what we used.
We used a metal rod as a lever arm because it was one of the last things we found in the science room. This lever arm will serve to pull back and to hold the string in order to wind it up and then when we let it go, it would move.
To attach the lever arm to the mousetrap, we simply used colorful duct tape. It was light and it supported the metal rod quite well.
We used a wooden base under the mousetrap because our wheels were large and we wanted more support. The wood came form a clementine wooden box. As you can see, it is cut at the end because the binder clips (will explain later) were not staying on when it was longer because they were too far apart.
The flower stickers and purple glitter strips were for decoration purposes only. The wooden base says "carson and jasmin's car oh yeahhhhh"
We used 1 chopstick and broke it in half in order for it to hold the binder clips and stay on the axle (will explain later). The two pink binder clips are clipped onto the chopsticks which are hot glued onto the wooden base. In order to put the binder clips on the axle, we had to take out the white pieces off of the clip itself and then put them on and reclip them.
The wheels are playmobil car wheels from a child's car. The top wheels are attached to the wooden base by hot glue but the bottom wheels had to have the wheels rotating at the same time as the axle for the car to move. Therefore we hot glued the wheels on each side to the axle and they stayed.
Here is a video of how our mousetrap turned out. We were really excited.
As simple as this mousetrap car looks, it was extremely hard to get this final product.
Reflection [Physics Concepts]:
In the making of this mousetrap, Newton was involved in almost every single part of it. Wow. It's pretty awesome to see that the physics we get out of a textbook, we were able to put them to use and make a car and put them to use.
Newton 1st, 2nd, and 3rd laws were used.
Newton's 1st: Newton's law that an object will stay in motion unless acted upon by an outside force was used when we had to simply put the car in motion and once we did, it remained in motion until it hit the wall which was the outside force or when the string would cause it to stop moving.
Newton's 2nd: Newton's law that acceleration is directly proportional to force and inversely proportional to mass was used as well. This is because if our force were greater, our acceleration would be greater too. We really tried to focus on keeping the mass of our car small because since force and acceleration are inversely proportional to mass, then if the mass was smaller, our car would go faster.
Newton's 3rd: Newton's third law states that with every action there is an equal and opposite reaction. Carson and I kept this in mind because this meant that whatever force the car had, the ground would pull with the same force and this law made it evident that our car had to be stable and strong at the same time.
Two Types of Friction:
The problems we encountered with friction is that we did not want to have too much or too little and it was hard to do that in this project. The wheels helped a lot because they came right off of a toy car therefore they provided with the right amount of friction but we didn't want it to have any other form of friction so we made sure that the wooden base did not drag on the ground but it was really close. We used friction to our advantage because the wheels had to have it in order to create some traction to keep moving The two forms of friction that were involved were static and kinetic friction. The static friction was created between the wheels and the wooden floor. Kinetic friction was involved because it is the friction that an object has when it is in motion and it is attempting to rest//stop.
Wheels:
When deciding what type of wheels we should use and the quantity, we first thought that 3 wheels would be the ideal number with two big wheels in the back and one small wheel in the front. We also considered records but then decided that those would be too big. We then decided on four wheels because four would keep our car most stable and also we decided on real car wheels because they already included an axle and we just had to make a few adjustments to make sure the wheels rotated the same way as the axle. The effect of using big wheels meant that it would go a greater distance but slower, but if we used small wheels the car would go faster but a shorter distance and that is exactly what we wanted.
Conservation of Energy:
The law of the conservation of energy tells us that energy cannot be created or destroyed but that it may be transformed//changed into another form of energy. The total amount of energy always stays there no matter what type of energy it is transformed into.Because we know energy does not ever leave the system, kinetic and potential energy change from one or the other. Our mousetrap car did exactly that becuase in no way could we change the energy of the car. But by using the string and the lever arm we increased the potential energy in the car and the car changed it into the kinetic energy. This is what made it go 5 meters or more. The car had the same amount of energy from beginning to end.
Lever Arm:
The lever arm was one of the easiest parts for Carson and I to do. We knew that the longer the lever arm, the longer distance it would go therefore we used the long metal rod to help us. Joey helped us by telling us where to attach the rod which was directly on the mousetrap. We attached it with duct tape so it was secure. Using the long lever arm an winding it up with thin string helped it go five meters after a couple of trials. It was great.
Rotational Inertia//Rotational Velocity//Tangential Velocity:
We already know that rotational velocity is the number of rotations in a unit of time. At first, we wanted our back wheels to be larger in order for them to make more rotations but soon realized that it would be better if all of the wheels would rotate the same distance. Tangential velocity//linear speed is something moving along a circular path. Tangential speed depends on the distance from the axis of rotation. These concepts were important when we were deciding on the type of wheels we should use because the larger the wheels the greater distance these wheels would cover in a shorter amount of time even though they would have a smaller rotational velocity. Rotational inertia is when an object resists changes in the spin of an object. It is dependent on distribution of mass and the distance from the axis of rotation.
Smaller rotational inertia = easier to spin
Large rotational inertia = harder to spin.
When we designed where the wheels would go, we decided they should be closer together because the less distance between the wheels, the faster they would move. It was super beneficial to have less rotational inertia overall.
Things we cannot calculate:
Work is calculated as force times distance and we measure it in Joules. It is key to know that the force and the distance must be parallel because if they are not, no work is being done on the object. I don't think we can calculate work on the spring. This is because the spring is not parallel to the other parts of the car. We cannot calculate the potential energy that was stored before either because we know that potential energy is PE=mgh and we don’t know it’s mass or its height. We could probably figure out the mass but we still dont know the height. Kinetic energy cannot be calculated because we do not know its velocity or mass. Also, we cannot calculate the acceleration of the spring because we don’t know the distance it traveled nor do we know the speed it traveled.
Reflection [Experience]:
- Our final design did not look anything like our original design because in our original we thought we would use two records in the back and one small wheel in the front. We thought we would use chopsticks to attach the small wheel to the mousetrap. Also, we were going to attach a small balloon on the back in hopes that it would make the car go faster. Although we did not use this design at all, the chopsticks still came to use to attach the binder clips to the axle. The reason we didn't use records is because wanted our car to go fast and this would cause it to go slower because of the slower rotations.We did not use the balloon because when we tried it, it did not work at all. Also, we didn't use chopsticks as attachments to the mousetrap because chopsticks are extremely weak.
- The major problem that we encountered in our design was when we did the trials. The string that was provided in Ms. Lawrence's classroom was too thick an it kept getting stuck to the binder clips. We changed the string to a very strong plastic-like yellow string that you can see below and it fixed the issue!
- If I were to do this project again, I'd probably just build a simpler car instead of trying to incorporate so many different pieces. I'd also take time management into account because this project stressed Carson and I out a lot. I think I would probably use even smaller wheels. Other than that I thought our car was well built because when something went wrong (ie: curved too much) all we had to do was adjust small things like the binder clips.
Too bad we didn't beat this girl's car,
I think if we redid this project and had a longer amount of time, we definitely could have!
