Electric Potential Blog Resource

This video resource helped me in comprehending the small parts as well as the big parts of voltage as a whole. Voltage (electric potential difference, electric tension, electric pressure) as we have learned is the electric potential difference between two points, or the difference in electric potential energy of a unit charge transported between two points. Voltage can be measured in joules, coulombs and volts. This video carefully explains and solves examples on voltage. 

Mousetrap Car Report: Reflection

Physics of the Mousetrap Car:

The mousetrap project was our chance to show that we actually understand what we've been learning this year thus far. Proof of this is Newton's First, Second and Third laws being involved in this project. 

Newtons first law: An object in motion tends to stay in motion until acted upon by an outside force, An object at rest tends to stay at rest until acted upon by an outside force. The mouse trap car relates to Newtons first law because the car does not move until the force of the mousetrap moves it, and then it doesn't stop until it hits something or until gravity finally stops it. Our lever arm is the main reason our car actually moved; without it as an outside force the car wouldn't be able to move. When the trap is released the string (which is spun around the back axle) is slowly released from the back axle causing the wheel to spin, because of the friction between the wheel and the ground the wheels spin causing the car to move forward.

Newtons second law: Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). Newton’s Second Law states that force is proportional to acceleration and acceleration is inversely proportional to mass (shown as a=f/m). Newtons second law of motion will affect our mousetrap car because the more the car weighs the slower it goes. But the less the car weighs the faster it will go because it has less mass so it doesn't take a big amount of force to move it. 

Newtons third law: For every action there is an equal and opposite reaction. Newtons third law affects the car because for every action there is an equal and opposite reaction. That means that as the car is rolling that friction is pushing against it with not as much force so the car still moves. But as the car keeps going the forces equal out and the car slows down until it finally stops.An example of this is the wheels on the ground. The wheels push the ground backward and the ground pushes the wheels forward.

 The two types of friction were the friction created between the wheels and the floor to get it moving which is known as static friction, and then kinetic friction which is the resistance against a moving object. Friction took part in two key places. The friction between the wheels and the ground provided stabilization, yet at the cost of speed. Kinetic Friction took place between the wheels and the axle. The more friction less the wheels of the car were, the easier it was to spin and travel faster. We overcame static friction to make our car move by adding more string to create more force to overcome the frictional barrier. We created traction between the floor and the tire by adding balloons to help stabilize the car.

Stabilization was a key factor in choosing to have four wheels. We felt that the wheels would be more beneficial to the construction of our cars body  than one wheel. We chose CDs because they lack mass which causes a greater acceleration (Newtons Second Law). We got the CD idea from one of the YouTube videos that we saw. We thought about using two different sizes of wheels but then realized that it might get too complicated. The bigger wheels had a smaller rotational velocity, so to spin them around you needed a larger force.The simple design made for easy reconstruction and resembling of the construction of our mousetrap car. 

The Law of Conservation of Energy states that energy will never be destroyed only transferred. Though the car was not at a high position, when you set the mousetrap with the string the car has a lot of potential energy, but no kinetic energy. Once the mousetrap is set that potential energy starts to decrease at the same rate that the kinetic energy increases. Once the mousetrap has completely transferred potential energy into kinetic energy it is at its greatest point and the potential energy is zero. However once the car starts slowing back down, the kinetic energy begins to decrease at the same rate the potential energy increases, until the car stops.

The length of our level arm was a huge obstacle in the construction of our car. At first, we started with no level arm but the string method, which we made roughly twice the length of our car. However, our car didn't have much movement. We watched videos and took advice from both our peers and teacher in hopes for insight on what may help us. We learned that the longer the lever arm, the farther our car would go. So, we used some extra pens we had taped together using duct tape and attached it to our car. The first run with the lever arm our car went 4.5 meters! Our next few attempts didn't go as well, resulting in our car struggling to go half the distance. It was frustrating and we tried making the lever arm longer, but this just made the car topple over and it even flipped over a few runs. We ended with finding the thinnest string supplied to our class and eventually got our vehicle to move. From here we made small fixes in hopes of our car going to full distance.

Rotational velocity is the number of complete rotations per time unit. We wanted our front wheels to have a high rotational velocity meaning it would have more rotations per time unit whereas the back wheels could have a greater tangential velocity. Tangential velocity can also be called linear speed because it is something moving along a circular path. The direction of motion is tangent to the circumference. Tangential speed depends on the distance from the axis of rotation. Inertia is the property of an object to resist change in motion dependent upon the mass. This was important in the construction of our wheels because the larger the wheels the greater the distance the wheels would cover in a shorter amount of time even though they would have a smaller rotational velocity.  Rotational inertia is the property of an object to resist changes in the spin of an object. It is dependent upon where the mass is located on that object, how it is distributed.  It involves the distribution of mass and how far away it is from the axis of rotation. If an object has a small amount of rotational inertia, it is easier to spin compared to an object with a large amount of rotational inertia, which is very difficult to spin. We made sure we didn't have a lot of weight spread out on the car, which is why the frame of our car was simply the mousetrap. This would create a smaller mass that was together creating less rotational inertia on the car. The less rotational inertia our car had the better.

Work is the effort exerted on something that will change its energy. Work equals force times distance. [Work=Force X Distance] Work is measured in Joules. The force and distance must be parallel to one another in order for there to be work done. We cannot calculate the work being done on the spring because the spring is not parallel to the distance the car travels. Potential energy is energy that is stored and held in a stored state that has potential of doing work. Potential energy is equal to the combination (multiplied) of mass, gravity, and height.[Potential Energy= Mass X Gravity X Height] We cannot calculate the amount of potential energy being done on the spring because we don’t know it’s mass or its height. Also, we can’t measure don’t know the total energy of the system so it’s not possible to calculate the potential energy. Kinetic energy is the energy of motion. Potential energy can change into kinetic energy. The change in kinetic energy of a moving object depends on the mass of the object as well as its speed. [Change in Kinetic Energy=1/2mass X velocity^2] Anything in motion has kinetic energy. According to the work energy theorem, work equals change in kinetic energy. The change in kinetic energy can’t be measure on the spring because we don’t have enough evidence of the velocity of the spring itself. Acceleration is equal to speed times distance, although we can measure the acceleration of the car, we cannot measure the acceleration of the spring because we don’t know the distance it traveled nor do we know the speed it traveled.  

Our final design was much like the original one.  We didn't know what we were going to use a lever arm which is probably our biggest change. We always wanted to use something to keep the axles from moving. We faced problems technically with the machinery and moving things around. We followed our plan and made it how we wanted it to, but it did not work very well the first time. If we did this project again I would keep the same design, but the one thing that I would change would be the lever. I would use a sturdy yet longer lever arm allowing it to pull more string, thus allowing it to travel faster.