Hot Wheels Lab - Cons of Energy - Online(1)-2

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 0.53 1.40 5.23 2.59 2.20 1.67 3.15 49.64 0.45 1.00 4.42 2.2 1.77 1.46 3.24 30.80 0.38 0.73 3.78 1.86 1.45 1.29 3.39 10.87 0.30 0.45 2.96 1.46 1.09 0.97 3.23 8.73 0.06 0.22 2.07 1.59 0.76 0.66 11 136.64 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. The car’s velocity at launch is calculated using two different techniques. Why are they different? To what is this difference attributed? Write a paragraph to discuss the difference between the velocities and indicate which technique gives an “ideal” velocity and which one gives the “real” velocity. Your discussion should begin with the Physics concept being used and the starting equation that leads to the expression used to calculate the velocity. Write a paragraph discussing when the car becomes a projectile and then show the equation used to calculate the time of flight (i.e., the time that the car is a projectile). Your discussion should begin with the Range Height 2

Math, Physics, Engineering Department Physics 1401 Instructor: Joe Kirchhoff Question 2 To be able to find the ideal speed for similar labs like this or when needed to find the ideal speed we can use the given equation that consist of V = sqrt (2gH). The letter g consists of being the gravitational constant which then equals the number of 9.8 and then the letter (h) would be the height. This equation is also known to deal with energy conversion. energy conversion consists of the process in which one form of energy changes into another. Questin 5 To be able to find the answer to this question we use this equation that consist of- 1 . (F f dXT)= 1/2 m( V ideal - Vreal) 2 . Ff= 1/2 m(V ideal and Vreal)/ Length of track So, these equations consist of subtracting the real speed from the ideal speed in the first equation and then once the answer for that question is obtained one must then plug in the total to the second equation and dived it by the length of the track. The letter m the stands for the mass of car. Question 3 Now to find the real speed we first have to find the time if it is not given and the equation to find time would consist of (t- sqrt 2h/g) which is similar to the equation of finding the ideal speed. Now if the time is given or has been found the Real speed would then come from the range since the range is what gives the real speed. The real speed equation consists of. V= R/T The letter R consist of the range and the letter T consist of the time so you would dived the range by the time. Now the car becomes a projectile right after going of the ramp and continues in motion by its own inertia. Being able to find the time of flight consist of confusing the same equation for finding time which is mentioned before. Question 4 These speeds are different because there are a few things to consider when calculating this speed for example in ideal speed there is no air resistance or the air resistance if neglible and for real speed the air resistance must be considered in the calculations. This would also be considering the forces that are ignored in one and how the answer to each will be different. The reason they have this difference is because of where each speed starts and ends for example the ideal speed is found from the ramp and the real is found where the range would be which is the very bottom where it just rolls of considering what the object is.