This resource defines voltage in an electric field, and discusses the difference between electric potential and electric potential energy.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elevol.html
Monday, March 31, 2014
Monday, March 3, 2014
Mouse Trap Car Reflection
Speed: 4.56 seconds (to go 5 meters)
Place: 5th
Here is a photo of our mousetrap car:
Here is a labeled diagram of our mousetrap car:
Each part used was light weight, so the car would have a greater acceleration (a=f/m).The CD wheels' mass were close to the axis of rotation, giving them a small rotational inertia and allowing them to spin quickly. Pens were used as axels, because they are smooth and have little friction, allowing the wheels to spin without hindrance. The balloon covering on the back wheels provided traction, allowing the wheels to push with a greater force on the floor and move forward. We used a long knitting needle attached to the mousetrap as our lever arm, which was connected to string wrapped around the back axel. When the mousetrap went of, the lever arm pulled the string which in turn rotated the axel, causing the car to move forward. Using a long lever arm allowed the car to travel a greater distance.
Physics of the Mousetrap Car
1.) How do Newton's laws apply to the performance of a car?
First Law: Objects in motion stay in motion, and objects at rest stay at rest, unless acted upon by an outside force.
This lets us know that in order for a car to move, there must be an external force to make it move. The force of the mousetrap being set of and the lever arm are what made our mousetrap car move.
Second Law: Acceleration = force/mass
This means that for a car to go quickly, it must have a small mass and a large force.
Third Law: For every action, there is an equal and opposite reaction.
This applies to how we can make the car move. For the car to move, it must exert a great enough force on the ground backward that it pushes the car forward.
2.) What are the two types of friction present, and how did you use these to your advantage? What problems did you encounter in terms of friction?
The two types of friction in our mousetrap car were rolling friction and sliding friction. Rolling friction was in the wheels pressing on the surface on which they were rolling. Sliding friction is in relation to the axles and the eye hooks, where the axel slide inside of their holding.
We used friction to our advantage to provide traction on the back wheels and start our car. We did not really face any friction-related problems.
3.) What factors did you take into account when choosing what wheels to use?
We decided that our wheels should have a small rotational inertia so they could spin quickly and be lightweight- also so they could spin quickly (a=f/m). CDs seemed like the perfect option. We used the same sized wheels on both axels, but the back wheel had balloons for traction. Reflecting, we probably should have chosen smaller front wheels for a greater acceleration.
4.) How does the conservation of energy relate to our car?
The kinetic and potential energy in our mousetrap car was in the lever arm, because it was the only part moving vertically. When the lever arm was pulled taught by winding the string, it had stored potential energy. Once the lever arm was let go, that potential energy decreased as kinetic energy increased.
5.) What was the length of your lever arm and how did it affect your car?
Our lever arm was 17cm long. By having a fairly long lever arm, our car was able to go a long distance (14m). This is because the lever arm is connected to the string which rotates the axel. The longer the lever arm, the longer distance it covers. The longer distance is covers, the more string it pulls, causing the axel to rotate more and the car to travel a farther distance.
6.) What were the roles of rotation in the functioning of your car?
We used wheels with their mass close to the axis of rotation, so, in turn, they had a small rotational inertia and a greater velocity. One way in which we could have improved our car would be to have had smaller front wheels with smaller rotational inertia and greater velocity. We wouldn't have changed our back wheels, because of the great function of our balloons and CDs for traction. Tangential speed did not play much of a role in the construction of our car.
7.) Why can't you calculate the amount of work the spring does on the car? Why can't you calculate the amount of potential energy stored and kinetic energy used in the car? Why can't you calculate the force exerted by the spring on the car?
Reflection
1.) Final Design vs. Original Design
In our original design. we intended to use small bottle caps for front wheels and use the mousetrap as the base (no wooden platform). We were also going to use balloons to held the wheels on the axels and a pen for our lever arm. The small bottle caps were too wobbly, so we opted for CDs, and the wooden platform was too thin to hold the eye hooks that held the axels (we also just thought it would travel farther with a larger base). The balloons failed for holding the wheels, so we used hot glue instead, which was much more stable. The pen for a lever arm worked well and we passed the required 7 m on our first test run, but we thought a longer one would be more successful and help our car travel an even greater distance.
2.) Major problems and How They Were Solved
The greatest problem encountered was slightly uneven wheels, which hindered our car from going quickly. By readjusting with hot flue, we were able to make them more even and increase our speed. The other issue we faced was the wheels slightly catching on the glue holding the eye hooks. This slowed down our car. Sean readjusted the eye hooks and fixed the problem.
3.) What would you do differently in the future?
In the future I would focus more on speed rather than distance. While our car did go the farthest in the class (14m) it was right in the middle in regards to time. I would probably make the car smaller, especially in the wheels, which would decrease rotational inertia and increase velocity. I would also look for even lighter materials to increase acceleration (a=f/m).
Place: 5th
Here is a video of our mousetrap car in action:
Here is a photo of our mousetrap car:
Here is a labeled diagram of our mousetrap car:
Each part used was light weight, so the car would have a greater acceleration (a=f/m).The CD wheels' mass were close to the axis of rotation, giving them a small rotational inertia and allowing them to spin quickly. Pens were used as axels, because they are smooth and have little friction, allowing the wheels to spin without hindrance. The balloon covering on the back wheels provided traction, allowing the wheels to push with a greater force on the floor and move forward. We used a long knitting needle attached to the mousetrap as our lever arm, which was connected to string wrapped around the back axel. When the mousetrap went of, the lever arm pulled the string which in turn rotated the axel, causing the car to move forward. Using a long lever arm allowed the car to travel a greater distance.
Physics of the Mousetrap Car
1.) How do Newton's laws apply to the performance of a car?
First Law: Objects in motion stay in motion, and objects at rest stay at rest, unless acted upon by an outside force.
This lets us know that in order for a car to move, there must be an external force to make it move. The force of the mousetrap being set of and the lever arm are what made our mousetrap car move.
Second Law: Acceleration = force/mass
This means that for a car to go quickly, it must have a small mass and a large force.
Third Law: For every action, there is an equal and opposite reaction.
This applies to how we can make the car move. For the car to move, it must exert a great enough force on the ground backward that it pushes the car forward.
2.) What are the two types of friction present, and how did you use these to your advantage? What problems did you encounter in terms of friction?
The two types of friction in our mousetrap car were rolling friction and sliding friction. Rolling friction was in the wheels pressing on the surface on which they were rolling. Sliding friction is in relation to the axles and the eye hooks, where the axel slide inside of their holding.
We used friction to our advantage to provide traction on the back wheels and start our car. We did not really face any friction-related problems.
3.) What factors did you take into account when choosing what wheels to use?
We decided that our wheels should have a small rotational inertia so they could spin quickly and be lightweight- also so they could spin quickly (a=f/m). CDs seemed like the perfect option. We used the same sized wheels on both axels, but the back wheel had balloons for traction. Reflecting, we probably should have chosen smaller front wheels for a greater acceleration.
4.) How does the conservation of energy relate to our car?
The kinetic and potential energy in our mousetrap car was in the lever arm, because it was the only part moving vertically. When the lever arm was pulled taught by winding the string, it had stored potential energy. Once the lever arm was let go, that potential energy decreased as kinetic energy increased.
5.) What was the length of your lever arm and how did it affect your car?
Our lever arm was 17cm long. By having a fairly long lever arm, our car was able to go a long distance (14m). This is because the lever arm is connected to the string which rotates the axel. The longer the lever arm, the longer distance it covers. The longer distance is covers, the more string it pulls, causing the axel to rotate more and the car to travel a farther distance.
6.) What were the roles of rotation in the functioning of your car?
We used wheels with their mass close to the axis of rotation, so, in turn, they had a small rotational inertia and a greater velocity. One way in which we could have improved our car would be to have had smaller front wheels with smaller rotational inertia and greater velocity. We wouldn't have changed our back wheels, because of the great function of our balloons and CDs for traction. Tangential speed did not play much of a role in the construction of our car.
7.) Why can't you calculate the amount of work the spring does on the car? Why can't you calculate the amount of potential energy stored and kinetic energy used in the car? Why can't you calculate the force exerted by the spring on the car?
- You cannot calculate the work the spring does on the car, because the pull of the string is perpendicular to the spring. In order to calculate work, you would have to know the amount of force at each position as the lever arm moves, which we cannot do without a complicated formula.This is also why you can't calculate the force exerted by the spring. You cannot calculate potential and kinetic energy, because of this and also because energy could be produced in unused forms such as sound or heat.
Reflection
1.) Final Design vs. Original Design
In our original design. we intended to use small bottle caps for front wheels and use the mousetrap as the base (no wooden platform). We were also going to use balloons to held the wheels on the axels and a pen for our lever arm. The small bottle caps were too wobbly, so we opted for CDs, and the wooden platform was too thin to hold the eye hooks that held the axels (we also just thought it would travel farther with a larger base). The balloons failed for holding the wheels, so we used hot glue instead, which was much more stable. The pen for a lever arm worked well and we passed the required 7 m on our first test run, but we thought a longer one would be more successful and help our car travel an even greater distance.
2.) Major problems and How They Were Solved
The greatest problem encountered was slightly uneven wheels, which hindered our car from going quickly. By readjusting with hot flue, we were able to make them more even and increase our speed. The other issue we faced was the wheels slightly catching on the glue holding the eye hooks. This slowed down our car. Sean readjusted the eye hooks and fixed the problem.
3.) What would you do differently in the future?
In the future I would focus more on speed rather than distance. While our car did go the farthest in the class (14m) it was right in the middle in regards to time. I would probably make the car smaller, especially in the wheels, which would decrease rotational inertia and increase velocity. I would also look for even lighter materials to increase acceleration (a=f/m).
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