Extra Credit Project: Work done by Automobile Engines

How much energy do different automobiles use?

This project may be done by teams of 1-2 individuals.

Your task in this assignment is to measure the energy consumed by at least 10 different automobiles as they accelerate from a standing start. You must find a convenient stop sign or traffic light near which you may work safely. Measure a distance of 50 to 100 m from the stop point in the direction of motion. Make sure that vehicles travel in a straight line along a level surface as they traverse this distance. Figure out a way to measure accurately the time it takes a vehicle to move from the stop point to the end of your track. Measure the time it takes at least 10 different cars to cover this distance. Write down the make and model of each car, plus any other information you think important.

After you have acquired your data, determine the masses of each automobile. You may measure them directly (best), search for written descriptions of their weight (second best), or simply estimate it (worst). You may want to include the mass of the driver, any passengers, and luggage, if you think it significant.

Based upon the mass of each car, and the time it took to cover your measured distance, you can calculate the force imparted by the engine of the car onto the road. You may then calculate the work done by each car as it accelerates from rest. You may assume that each car accelerates uniformly over the entire distance -- but is that really true?

How does the work done by the cars compare to their stated number of miles per gallon? Make a graph which shows the nominal gas mileage of each car on the horizontal axis (in miles per gallon), and the work done accelerating the car over your marked distance on the vertical axis (in Joules). Write a few sentences which interpret the information shown on the graph.

Submit a report which contains pictures and descriptions of your work, as well as the results. Explicitly state the location at which you watched cars, the methods you employed to measure distance and time, and the source(s) for the mass of each car. You may also include interesting items you discovered during the course of the procedure.

This page maintained by Michael Richmond. Last modified Nov 18, 1999.