Hybrid Car Battery Design:
The objective of this project was to learn about the different types of energies, and how to convert the energy source efficiently. Additionally, we also used the concepts of velocity, acceleration, and friction throughout this project. The criteria included:
- Building a hybrid car
- Making the car go exactly 5 meters
- Taking data and making performance graphs
- Creating a sales pitch presentation
- Presenting
The Process:
Like our previous projects, our group began by sitting at the table, researching, and brainstorming ideas. At first, we found something on the internet about a "uni-wheel battery-powered car" and tried to assemble that, but we soon realized that some of the parts were going to be extremely hard to get, as well as difficult to temper with. After that, we decided to use a rat trap to power our car. Rat traps are essentially tight, coiled springs that snap the lever from one side to another. That motion is what moves our car.
We began by building the frame -- we attached axels in between the wheels, and cut out wooden sides so that the rat trap wouldn't have to sit on top of those axels. This way, they could spin freely and make the car move farther. Once the frame was set, we screwed the rat trap into place and attached a string to the lever arm of the contraption. Then we tied that to the back wheels' axle.
It definitely took us a while to get used to setting up the rat trap, but once we got over it, everything began to fall into place. We could see the car was definitely getting means of energy through the rat trap. The final step was to adjust the car to make it go exactly five meters.
At first, it was consistently under. It would come to a stop at around 4 meters due to three main reasons: (1) friction on the wheels, (2) the rat trap wouldn't pull on the string enough, and (3) the string would sometimes snap due to the force. To fix these problems, our group came together and decided to attach a wooden strip to the rat trap. We staple-gunned and duct-taped this wooden strip to the side of the lever arm, and then tied the string to that. This increased the distance of the lever arm, so that when the rat trap activated, it would pull the string on the axle for a longer period of time. This resulted in more revolutions, and made our car go that final meter. The rest was simple tweaking of the weights.
Our final step was polishing up on the aesthetics of our car, and making the sales-pitch presentation. Our group ended up cutting styrofoam and making our rat trap car into a monster truck with flames on the side. It was an extremely interesting design process; we had lots of fun with that part! Meanwhile, our group also put together the presentation below:
- Building a hybrid car
- Making the car go exactly 5 meters
- Taking data and making performance graphs
- Creating a sales pitch presentation
- Presenting
The Process:
Like our previous projects, our group began by sitting at the table, researching, and brainstorming ideas. At first, we found something on the internet about a "uni-wheel battery-powered car" and tried to assemble that, but we soon realized that some of the parts were going to be extremely hard to get, as well as difficult to temper with. After that, we decided to use a rat trap to power our car. Rat traps are essentially tight, coiled springs that snap the lever from one side to another. That motion is what moves our car.
We began by building the frame -- we attached axels in between the wheels, and cut out wooden sides so that the rat trap wouldn't have to sit on top of those axels. This way, they could spin freely and make the car move farther. Once the frame was set, we screwed the rat trap into place and attached a string to the lever arm of the contraption. Then we tied that to the back wheels' axle.
It definitely took us a while to get used to setting up the rat trap, but once we got over it, everything began to fall into place. We could see the car was definitely getting means of energy through the rat trap. The final step was to adjust the car to make it go exactly five meters.
At first, it was consistently under. It would come to a stop at around 4 meters due to three main reasons: (1) friction on the wheels, (2) the rat trap wouldn't pull on the string enough, and (3) the string would sometimes snap due to the force. To fix these problems, our group came together and decided to attach a wooden strip to the rat trap. We staple-gunned and duct-taped this wooden strip to the side of the lever arm, and then tied the string to that. This increased the distance of the lever arm, so that when the rat trap activated, it would pull the string on the axle for a longer period of time. This resulted in more revolutions, and made our car go that final meter. The rest was simple tweaking of the weights.
Our final step was polishing up on the aesthetics of our car, and making the sales-pitch presentation. Our group ended up cutting styrofoam and making our rat trap car into a monster truck with flames on the side. It was an extremely interesting design process; we had lots of fun with that part! Meanwhile, our group also put together the presentation below:
Physics Concepts:
Velocity: Velocity is a vector that shows speed in a given direction. Our car had a steadily increasing velocity before it peaked, and slowed down due to friction.
Acceleration: Acceleration is the change in velocity over the change in time. In correspondence to velocity, the acceleration rises, then maxes out before decreasing.
Potential Energy: The PE of our car started out with a great number because of all the pent-up energy stored in the springs. A rat trap can store up a lot of PE, which is why when it snaps, the force is so great.
Kinetic Energy: Although the PE was significant, the amount converted to KE was much less. This is because the efficiency of the hybrid car was not 100%. Much of the PE did not turn to KE, and no engines in the real world do have 100% efficiency. This is also due to friction and air resistance, and the fact that we had a string attached to the lever that slowed down the lever arm so the force was less.
Thermal Energy: This is the total energy released, including friction. Theoretically, thermal energy should continue rising because all energy should eventually be released.
Velocity: Velocity is a vector that shows speed in a given direction. Our car had a steadily increasing velocity before it peaked, and slowed down due to friction.
Acceleration: Acceleration is the change in velocity over the change in time. In correspondence to velocity, the acceleration rises, then maxes out before decreasing.
Potential Energy: The PE of our car started out with a great number because of all the pent-up energy stored in the springs. A rat trap can store up a lot of PE, which is why when it snaps, the force is so great.
Kinetic Energy: Although the PE was significant, the amount converted to KE was much less. This is because the efficiency of the hybrid car was not 100%. Much of the PE did not turn to KE, and no engines in the real world do have 100% efficiency. This is also due to friction and air resistance, and the fact that we had a string attached to the lever that slowed down the lever arm so the force was less.
Thermal Energy: This is the total energy released, including friction. Theoretically, thermal energy should continue rising because all energy should eventually be released.
Reflection:
Personally, I loved this project so much. Building the hybrid car was a test of patience and persistence, but it really helped me learn about the ideas of engine efficiency, the transfer between potential and kinetic energy, and how sometimes, simplicity is an engineer's best friend. At first, we wanted to do such complex designs, but as the days progressed, we simplified our prototype to one powered by a single rat trap. Instead of so many different moving parts, we only had to worry about the lever arm, the axles, and the wheels. While we were building and tweaking, it was much easier to see what went wrong when it veered off course or fell short of its destination. And it went the full five meters as well.
In this project, I felt that our group really managed our time well. Before even building our prototype, we'd already set out a schedule for when we'd have to finish the hybrid car, and when we'd have to make the presentation and practice. We made a last-minute decision to transform our car into a truck with a styrofoam frame painted in red, so instead of all working on that, we split our group up to make sure that the presentation was finished on time as well. While Rosalie and Rachel painted and glued, Natalie and I took calculations, graphed, and finished the powerpoint. The last day, we ran through our presentation a couple times and put everything together so that when we actually presented, everything went smoothly.
Probably the only pitfall in our project was that our car went a couple centimeters past the finish line, and that our graphs were a little off due to Excel's weird formatting. Perhaps in the future, we could make our own graphs by hand and show it that way, or find another program that does the x-axis and y-axis evenly. But overall, I really believe that this project was a success, and I had so much fun working on it.
Personally, I loved this project so much. Building the hybrid car was a test of patience and persistence, but it really helped me learn about the ideas of engine efficiency, the transfer between potential and kinetic energy, and how sometimes, simplicity is an engineer's best friend. At first, we wanted to do such complex designs, but as the days progressed, we simplified our prototype to one powered by a single rat trap. Instead of so many different moving parts, we only had to worry about the lever arm, the axles, and the wheels. While we were building and tweaking, it was much easier to see what went wrong when it veered off course or fell short of its destination. And it went the full five meters as well.
In this project, I felt that our group really managed our time well. Before even building our prototype, we'd already set out a schedule for when we'd have to finish the hybrid car, and when we'd have to make the presentation and practice. We made a last-minute decision to transform our car into a truck with a styrofoam frame painted in red, so instead of all working on that, we split our group up to make sure that the presentation was finished on time as well. While Rosalie and Rachel painted and glued, Natalie and I took calculations, graphed, and finished the powerpoint. The last day, we ran through our presentation a couple times and put everything together so that when we actually presented, everything went smoothly.
Probably the only pitfall in our project was that our car went a couple centimeters past the finish line, and that our graphs were a little off due to Excel's weird formatting. Perhaps in the future, we could make our own graphs by hand and show it that way, or find another program that does the x-axis and y-axis evenly. But overall, I really believe that this project was a success, and I had so much fun working on it.
"Our aspirations are our possibilities." - Samuel Johnson