Place in F block: 5th
This is a model of our car that we used.
The wheels: 2 CD's in the back with balloons wrapped around the edges and a toy car wheel in the front with two bottle caps glued on either side
The sides: two light weight pieces of wood attached to the mouse trap
The axel: in the back we used a medal small axel and then drilled it through a piece of glue to make it thicker and in the front we used the same metal axel but without
The lever arm: we used a pencil as our lever arm and fishing line as our string
The mousetrap car can be related to all three of Newton's laws. Newton's first law states that and object in motion tends to stay in motion unless acted upon by and outside force and an object at rest tends to stay at rest unless acted upon by an outside force. This is related to the car, because once the car is moving the only thing that will stop it from moving is an outside force. This outside force could be a physical object or it could be friction. Our mousetrap car stopped because there was a lot of friction. The mousetrap caused it to move but once the friction caught up with the car it was brought to a stop. The car will not start to move unless acted upon by and outside force, in this case the mousetrap itself is what causes the car to move forward. Newton's second law states that acceleration is proportional to force and inversely proportional to mass. This means that the more force applied the car the more the car will accelerate and the smaller the amount of mass the faster the car will go. We tried to use the lightest weight wood and wheels because we knew that less mass meant it would travel faster. The amount of force applied is also important to make the car move faster. We used a lever which created more force and more acceleration. Newton's third law states that for every action there is an equal and opposite reaction. This is seen in the care in several different ways. One example is that when the car pushes down on the floor while moving the floor pushes back on the car. Another example is when the mousetrap pulls the string that is wrapped around the axel the axel is pulling the string. It is important to remember that these forces are equal and opposite.
There are two types of friction that are present. The first type is static friction which is only seen when the car is at rest. Static friction is what what makes it difficult for the car to begin to move. The other type of friction is kinetic friction which is see when the car is in motion. Kinetic friction slows the car down when it is in motion. One problem we had with friction was with the wheels. We added balloons to the wheels in order to make it smoother and thus decreasing the friction. We also encountered friction when designing our axels. We chose to use a thicker axel to attach the string to because in this case we used friction to our advantage. This is because it was applied closer to rotation thus making the torque smaller requiring less force. One mistake we made was that we glued two bottle caps to the front wheel which created more friction. It was good to have friction on the back wheels so that they wouldn't slide but the added friction to the front wheels made it harder for the car to accelerate.
When choosing our wheels we wanted something lightweight because we know that the smaller the mass the greater the acceleration because of Newton's third law. We also decided to use larger wheels in the back (CD's) because they were the wheels that controlled the whole car. We chose to have only one wheel in the front, because it would mean less mass and a smaller rotational inertia. A smaller rotational inertia means that the wheel will rotate more.The wheel in the front was only there so the car would move, it did not control the car. One mistake we made was that we glued two bottle caps to either side of the front wheel which added mass and it created more friction. Our car still made it 5m but it would have been a lot faster if the front wheel had a lower rotational inertia. The way to lower this rotational inertia is by making the wheel smaller.
Before the mouse trap car was moving it had the highest amount of potential energy. Potential energy is the amount of energy an object has right before it begins to start moving. Once the car was in motion it's potential energy lowered while the kinetic energy became greater. Kinetic energy is the amount of energy an object had while in motion.When the car was at it's highest velocity it had the most amount of kinetic energy. Once the car started to slow down again though it's kinetic energy lowered and it gained potential energy in return.
For our lever arm we used a normal pencil. It was shorter than the length of the car and without it our car would not have traveled 5m. For our first test trial we tried attaching the string just straight to the mousetrap without and sort of lever arm and it only made it about 3m. By using the lever arm we increased the torque and by increasing the torque we increased the rotation. There are three ways of increasing the torque. One way is by adding more force. The second way is by increasing the lever arm. And the third way is by doing both of these things. We just increased the lever arm which increased the torque and required less force.
Before the mouse trap car was moving it had the highest amount of potential energy. Potential energy is the amount of energy an object has right before it begins to start moving. Once the car was in motion it's potential energy lowered while the kinetic energy became greater. Kinetic energy is the amount of energy an object had while in motion.When the car was at it's highest velocity it had the most amount of kinetic energy. Once the car started to slow down again though it's kinetic energy lowered and it gained potential energy in return.
For our lever arm we used a normal pencil. It was shorter than the length of the car and without it our car would not have traveled 5m. For our first test trial we tried attaching the string just straight to the mousetrap without and sort of lever arm and it only made it about 3m. By using the lever arm we increased the torque and by increasing the torque we increased the rotation. There are three ways of increasing the torque. One way is by adding more force. The second way is by increasing the lever arm. And the third way is by doing both of these things. We just increased the lever arm which increased the torque and required less force.
Rotational inertia was seen in our wheels. The larger the wheels the more rotational inertia. The more rotational inertia the wheels have the harder it is for them to rotate. We had larger wheels in the back that had more rotational inertia than the front wheel. This causes them to be the wheels that drive and control the car though. Like the train wheels the larger wheels control the car. We chose a small wheel in front because it was just there to keep the car moving so we wanted it to have a really low rotational inertia. One mistake we made though was gluing two bottle caps to either side because this increased the rotational inertia making it harder for the wheel to rotate. The wheels have different rotational velocities because one wheel is smaller than the other wheels so it is rotating more than the back to wheels. All of the wheels have the same tangential velocity though because all three wheels are covering the same amount of distance in the same amount of time.
Work is the measure of how much force is done in a certain amount of distance. We are unable to calculate the amount of work the spring does on the car because we don't know the amount of force the spring is putting on the car. We also don't know the potential energy and the kinetic energy in the spring that the car used. If we knew this information it could help us calculate the work because work is equal to the change in kinetic energy which is equal to the change in potential energy. We are unable to find the kinetic and potential energies because we do not know the mass of the spring in relation to the car. KE=1/2mv^2 we know the velocity but we cannot find the KE without knowing the mass. Same thing goes for PE. PE=mgh we know the gravity but we do not know the m and the h so we cannot find the potential energy. The reason that we cannot find the force the spring uses on the car is because we do not know the mass and we would have to calculate the acceleration since force=(mass)(acceleration).
Reflection
We followed our original design pretty well. We kept everything except once we did our first trial run without a lever arm we realized that we had to have a lever arm if we wanted our car to travel the 5m. One thing that we added that made it worse was we glued two bottle caps to the front wheel. This created more rotational inertia which made it harder for the wheel to rotate, slowing down the car. We thought that this was necessary to make the car stay in place but it was not necessary. If we were to do this project again I think I would make the car have a smaller mass. This would mean not using wood but just try to connect the mouse trap straight to the axels because the smaller the mass the faster the car would go. I would keep our wheel set up though because I think that the small wheel in front (without the bottle caps glued to it) and the two CD's in the back worked well. Overall I was happy with our car though because it made it the 5m and it was overall successful although it was not very fast.
Work is the measure of how much force is done in a certain amount of distance. We are unable to calculate the amount of work the spring does on the car because we don't know the amount of force the spring is putting on the car. We also don't know the potential energy and the kinetic energy in the spring that the car used. If we knew this information it could help us calculate the work because work is equal to the change in kinetic energy which is equal to the change in potential energy. We are unable to find the kinetic and potential energies because we do not know the mass of the spring in relation to the car. KE=1/2mv^2 we know the velocity but we cannot find the KE without knowing the mass. Same thing goes for PE. PE=mgh we know the gravity but we do not know the m and the h so we cannot find the potential energy. The reason that we cannot find the force the spring uses on the car is because we do not know the mass and we would have to calculate the acceleration since force=(mass)(acceleration).
Reflection
We followed our original design pretty well. We kept everything except once we did our first trial run without a lever arm we realized that we had to have a lever arm if we wanted our car to travel the 5m. One thing that we added that made it worse was we glued two bottle caps to the front wheel. This created more rotational inertia which made it harder for the wheel to rotate, slowing down the car. We thought that this was necessary to make the car stay in place but it was not necessary. If we were to do this project again I think I would make the car have a smaller mass. This would mean not using wood but just try to connect the mouse trap straight to the axels because the smaller the mass the faster the car would go. I would keep our wheel set up though because I think that the small wheel in front (without the bottle caps glued to it) and the two CD's in the back worked well. Overall I was happy with our car though because it made it the 5m and it was overall successful although it was not very fast.
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