Physics of Conservation
How Cars Can Conserve Energy From Hills and Utilize It Later
The basis for my project was to discover more about another way in which automobiles can conserve energy. Cars can have batteries inside that are charged by energy lost from going down hills, and that can utilize that energy later -for example, when the car is stopped at a red light, the battery will take over gasoline's role by powering the radio and such.
Many car companies have recently used this type of conservation to utilize energy since it makes cars more fuel efficient by not having to burn as much gas -something that is quiet appealing to today's car buyers. Recently, Chevrolet has put batteries in their automobiles calling it the eAssist system (the e standing for electric). However, the idea was not original to General Motors Company but rather similar techniques have been used by Honda since the late 1990's.
My setup was comprised of a ramp, .15 kg cart, uniform wooden blocks (to change height), and a motion detector placed at the bottom of the ramp. For each trial, I change the height by adding an approximately .04 m block under one end of the ramp, stacking one a new one each time. I used logger pro to analyze the data my motion detector had collected and took each final velocity.
Then, I made a graph using the data I collected to show the relationship between the differing heights and the final velocity -or the kinetic energy that was created during the trial. As shown in figure A it was a linear relationship so that shows that the higher the incline, the higher kinetic energy which in turn would charge more of a battery. This makes sense because using the equation gh=1/2v^2 for a situation in which an object begins with potential and ends with kinetic energy such as in this experiment, with gravity staying the same at 9.8, the larger the height, the larger the other half of the equation meaning velocity should be.
Next, after creating that graph I went on to make the one seen in figure B which was the theoretical graph of what should have happened. Therefore I used algebra to solve for v=sqrt(2gh) and plugged those velocity values into a linreg graph. Again, the relationship was linear, but more so that the experimental graph. In addition, both my theoretical and experimental graphs were square root functions and were linearized.
Reasons for the difference between the graphs include somewhat off final velocities from logger pro. However the graphs have the same trend so my data collection was correctly done. My means for stopping the cart was to just slam my hand down on it at the end of the ramp which could have led to minor misinformation from the detector.