The Project
The objective of this project was to design and build a prototype of a hybrid vehicle for an energy efficient car. This car had to travel a distance of 5 meters and be able to hold a weight of 250 grams. The vehicle also had to stop itself at the 5-meter line. We also needed to create a sales pitch for our hybrid vehicle. We chose to make a slideshow pitch.
Our final design was a gravity car, but it took a while to get there. We first started with a heat-powered car, in which we made a Stirling engine. A Stirling engine is a heat-powered engine that is heated by a fire (or other heat source), as it heats up pressure rises and gas expands, absorbing energy. As the gas expands, it pushes the piston, which drives the wheel. After working for hours in class and sometimes during lunch, building and tweaking our car, we still couldn't get it to work successfully. As a group, we decided to build a gravity-powered car instead. This ended up being more successful. For the gravity-powered, car we wrapped a string around the axle and then wrapped the string around a tall tower that was connected to the car. Then we attached the string to a mass. As the mass slowly moved down, the car moved forward. We used a mass of 1 kilogram (kg) and a drop height of 0.78 meters (m). The wheels of the car had a mechanical advantage (MA) of 12.
Concepts
Spring Constant: Spring constant is a measure of the elasticity of a spring.
Spring Potential Energy: This type of potential energy is stored as a result of deformation of an elastic object, such as the stretching of a spring.
Thermal Energy: Thermal energy is the energy that comes from heat.
Energy Graphs: An energy graph can show where energy is being transferred from potential to kinetic.
Distance vs. Time: In this graph, distance is the y-axis, and time is the x-axis. As the time increases, the distance does also, until it reaches a certain point and stops.
Time vs. Velocity: In this graph, time is the x-axis, and velocity is the y-axis. This graph will show you that velocity increases as the time increases, until about halfway (or later), where it should start decreasing in velocity.
Time vs. Energy: This graph shows more than one type of energy and how each changes as time goes by.
Spring Potential Energy: This type of potential energy is stored as a result of deformation of an elastic object, such as the stretching of a spring.
Thermal Energy: Thermal energy is the energy that comes from heat.
Energy Graphs: An energy graph can show where energy is being transferred from potential to kinetic.
Distance vs. Time: In this graph, distance is the y-axis, and time is the x-axis. As the time increases, the distance does also, until it reaches a certain point and stops.
Time vs. Velocity: In this graph, time is the x-axis, and velocity is the y-axis. This graph will show you that velocity increases as the time increases, until about halfway (or later), where it should start decreasing in velocity.
Time vs. Energy: This graph shows more than one type of energy and how each changes as time goes by.
Reflection
This project was one of our most challenging to date. It took a lot of time and effort to create a car that had to go 5 meters, carry weight, and stop itself. Our group always kept a positive outlook, even when it got unusually challenging and when we had to rethink our design entirely. One thing, besides the engine, blueprints, and calculations that I got to do that was fun was make an outside exterior that looked like the batmobile that my group and I thought was cool. Moving forward, I would like to work on my leadership skills by not waiting for someone to assign me something but by looking around and figuring out what needs to be done.