Hot Wheels Lab - Cons of Energy - Online(1)

Math, Physics, Engineering Department Physics 1401 Instructor: Joe Kirchhoff Laboratory Outline and Overview Conservation of Energy and 2-D Motion Applied To a “Flying” Hot Wheels Car Calculating Rolling Friction From Energy Report Requirements: This Overview, when completed, will be your submitted report. Each student will submit and independently written report. Complete the table below from the data provided for five car launches. Use the Support Video to remind you of the Projectile Motion calculations and to see how the concepts of Work and Energy manifests in this simple event. Overview: The simple act of letting a toy car roll off a table edge with an initial velocity involves knowledge of Conservation of Energy and 1-D physics and can be both explained and predicted with easily measured distances and equations used in this class. This lab will use measured Conservation of Energy to predict a car’s velocity when leaving a track horizontally and comparing to the real velocity as measured from projectile motion (remember that?). Any “lost” energy must be due to rolling friction (air resistance is quite negligible). Goals: To understand the motion of a Hot Wheels car so that its landing spot (to within a couple of centimeters) can be predicted with equations already studied and the application of Conservation of Energy to finding “lost” energy (friction, air resistance, heat, etc.). Hot Wheels Play: Data has been obtained for you for a recorded procedure (to identify variables). The car is forced to leave the track horizontally at the edge of the table. Multiple release points are used to ensure the car has different launch velocities. [Do you remember how to calculate this speed?] A picture of the experimental set-up is shown below with relevant parameters indicated. Figure 1: Experimental Arrangement. The height above the launch point is adjusted to achieve a different launch velocity. Further, the launch point is 0.742 m above the floor. Height 1

Math, Physics, Engineering Department Physics 1401 Instructor: Joe Kirchhoff You will need to know how high the end of the track is from the floor. This is used to calculate the time it takes the car to fall. [The calculation of time is more accurate than trying to measure it. Do you remember the equation used to calculate this time?] Figure 2: Arrangement showing a car as a projectile. The range is measured from a point directly below the launch point of the car to the first contact with the floor. Complete the table below for multiple release points of the Hot Wheels car. Does the time for the car to fall to the floor depend on the release point? Table 1: Measured and Calculated Quantities for a Horizontally Launched Hot Wheels Car. Time of Flight (s) Height (m) Ideal Launch Speed (m/s) Predicted Range (m) Track Length (m) Measured Range (m) “Real” Launch Speed (m/s) % Difference in Speeds 0.39 1.40 5.24 2.04 2.20 1.67 4.28 18.26 0.39 1.00 4.43 1.73 1.77 1.46 3.74 15.44 0.39 0.73 3.78 1.48 1.45 1.29 3.31 12.55 0.39 0.45 2.97 1.16 1.09 0.97 2.49 16.25 0.39 0.22 2.08 0.81 0.76 0.66 1.69 18.50 Height is the vertical distance above the end of the track. The launch height is 0.742 m above the floor. Track Length is the entire length of track for which the tires are in contact with the track. Range Height 2

Math, Physics, Engineering Department Physics 1401 Instructor: Joe Kirchhoff From the two velocities, and the track length (the distance covered while the car’s tires are in contact with the track), show how to calculate an approximate value for the friction between the track and the tires. Show the equations used and discuss your results. [Estimate the mass of the car, if needed, and use in your calculations.] Ff =normal force * coefficient of friction All lab reports/products will FIRST be graded against the guidelines of the Error Checklist. These guidelines cover table structure and captioning, figure captioning, required parameters of data graphing, how equations are placed in a report, among others. These are universal guidelines for a professional presentation of data. The Instructor will deduct points for violations of these guidelines at 3 or 4 points per violation BEFORE reading any discussion or conclusions.