University:
Boston University
Course:
CAS PY 242 | Principles of General Physics 2
Academic year:

2024
Views:

125

Pages:

2
Author:

Kylie Adams

General Physics Car Project Energy Sheet The energy stored in the rubber band is determined by the bands k value (k is called the spring constant), and how far the rubber band is stretched. For each rubber band type, using the formula PE = ½kx2, calculate the “maximum” elastic potential energy (PE). Use the maximum elongation as x, and the k value for each rubber band. Table 1. Type Elastic Potential Energy (PE) 1 2 3 4 5 6 Using your car and a stopwatch, perform at least four trials of allowing your car to roll across the floor a specific distance. Use a stopwatch to measure the time to travel that distance. You can, and should, adjust your car to try to MAXIMIZE the distance the car travels between each of the four trials. Record the data in the following table and calculate the average velocity using v = d/t. Table 2. Trial d in meters t in seconds v in m/s 1 2 3 4 Using the velocity values in the table above, and the formula KE = ½mv2 calculate the “average” kinetic energy of your car for each trial and record your results in the following table. The value for m is the mass of your car. Table 3. Trial KE in Joules 1 2 3 4 Determine the percentage of the maximum possible elastic potential energy that is getting turned into kinetic energy by using the following formula: KE/PE*100 = %Energy used KE values come from Table 3. PE values come from Table 1 for the particular rubber band type you are using. Record your results in the following table. Trial 1 2 3 4 % Energy used Based on the testing you have done so far, what we have learned in the past about energy and efficiency, and your basic intuition, answer each of the following questions, in complete sentences, on another sheet of paper. 1) What factors cause the amount of kinetic energy generated to be lower than the elastic potential energy we have available? 2) What type of changes might be made to the design of the car to increase the amount of elastic potential energy that is converted to kinetic energy? 3) Besides increasing the amount of energy converted to useful energy of motion (kinetic energy), what change could be made to the car to increase the overall speed of the car? Hint: The answer is in the formula KE=½mv2.