Physics Lab (Online Simulation) ENERGY Mechanics TA name: Due Date: Student Name: Student ID: Simulation Activity #4: Energy Skate Park Simulation created by the Physics Education Technology Project (PhET) clo The University of Colorado at Boulder http://phet.colorado.edu/ File Tracks Help Tracks "Kinetic Energy Reset Potential Energy Return Skater Thermal Energy Choose Skater.. Measuring Tape Potential Energy Reference Grid Path Show Path Clear Energy Graphs Show Pie Chart with Thermal Bar Graph Energy vs. Position Energy vs. Time Location Space Moon Earth Jupiter Gravity 9.81 N/kg Space Earth Jupiter Clear Heat Track Friction > PE = 0 at this dotted line 3.90 m Edit Skater > > fast Help! 6,000 Thermal = 0.00 J KE = 1694.31 J 5,000 Total = 4743.56 J PE = 3049.25 J 6:00 Energy (J) Kinetic Energy Potential Energy Thermal Energy 2. Energy (Joules 300 2000 1000 1 2 3 4 6 6 7 10 17 12 13 14 15 10 17 18 19 20 25 50 5 10.0 12.5 15. Sim Speed Position (meters) D Go! ] Playback I Step 14 Rewind Clear Copy Clear Kinetic Potential slow fast Thermal Total Total Kinetic Thermal Potential Clear HeatPhysics Lab (Online Simulation) Investigating Energy Exchanges: Kinetic Energy and Gravitational Paten tial Energy Objective: This activity is intended to enhance your physics education. We offer it as a virtual lab online. We think it will help you make connections between predictions and conclusions, concepts and actions, equations and practical activities. We also think that if you give this activity a chance, it will be fun! This is an opportunity to learn a great deal. Answer all questions as you follow the procedure in running the simulation. Learn about conservation of energy with a skater dude! Build tracks, ramps and jumps for the skater and view the kinetic energy, potential energy and friction as he moves. You can also take the skater to different planets or even space! Take some time and play with the skater and his track. It helps you to practice with the following features and controls. Track selector: click on Tracks and select from the drop down menu. For example, the \"Double well (Roller Coaster)\" shown above. Reset: This rests the simulation to default values and sets the track to friction parabola track. Skater selector: clicking on Choose skater... will allows you to choose a skateboarder with a different mass. Measuring Tape: Check the Measuring Tape Box when you want to make measurements. Drag the left end of the tape measure to where you start your measurement, and then drag the right end to the nal location. To make a reference horizontal line to your measurement, check the potential energy reference box and drag the blue line you see on the screen to the initial position. Graph Selector: If you would like to observe graphs that depicts the relationships among potential, kinetic, and thermal energy of the simulation, click buttons under the Energy Graphs. The types of graphs are shown above. You can also add pie graph by checking the Show pie chart box. These graphs can be shown with or without the Thermal energy. Gravity: you may change the gravitational force by changing the location or the sliding bar underneath Gravity box. Additional Features: Clicking the Clear Heat makes the track ictionless. You can also edit the track friction and the skater mass using T rack iction and Edit Skater buttons. You can also control the speed of the skater using the slide bar under the screen. Introduction: The law of conservation of energy states that the total amount of energy in an isolated system remains constant. As a consequence of this law, we can say that energy neither created nor destroyed, but can change its form. The total energy E of a system (the sum of its mechanical energy and its internal energies, including thermal energy) can change only by amounts of energy that are transferred to or from the system. If work W is done on the system, then W 2 AE : AEmech + AEm + AEim If the system is isolated (W = 0), this gives Physics Lab (Online Simulation) AEmech + AEIh + AEint = 0 The skate park is an excellent example of the conservation of energy. For the isolated skate- track-Earth system, the law of conservation of energy equation has the form AEmech + AEth = 0 Mechanical Energy: The mechanical energy Emech of a system is the sum of its kinetic energy K and its potential energy U: Emech = K + U The conservation of mechanical energy can be written as AEmech = AK + AU = 0. It can also rewritten as K + U = K; + U; In which the subscript refer to different instants during an energy transfer process. Gravitational Potential Energy: The potential energy associated with a system consisting of Earth and a nearby particle is gravitational potential energy. If the particle moves from yl to height yz , the change in gravitational potential energy of the particle-Earth system is AU = mam yl)=mgAy Kinetic Energy: The kinetic energy is associated with the state of motion of an object. If an object changes its speed from v] to v2 , the change in kinetic energy is AK=KziK1= 1/2 mV22 ~ 1/2 1'1'1V12 Procedure: Open Energy Skate Park My: (phgttolemdaedu simulations sims.php?sfm=Egergy=S_kgLe_Parlr Part I: Friction Parabola Track 1. Click Reset and observe the energy bars as the skater moves back and forth. As the skater descends his kinetic energy (green) and his potential energy (blue) . The total energy bar . 2. Considering the bottom of the parabola as a reference line, measure the maximum height (h) the skater climb. h = _ The gravitational potential energy at the maximum height is equal to Joules. The skaters speed at the minimum point of the parabola is equal to m/s Change the skateboarder (say Bulldog) and repeat steps 2, 3, and 4. a. h = m b. gravitational potential energy = Joules c. speed = m/s 6. Is the law of conservation of energy affected by the mass of the skater? Yeso 7. Now click Reset and observe the Energy versus Position graph as the skater moves back and forth. Do not forget to put the reference line at the minimum point of the parabola a. Pause the simulation at the bottom of the parabola. i. Kinetic energy = Joules ii. Potential energy = Joules 111. b. Run the simulation again, and then pause it at the maximum height. i. Kinetic energy = Joules ii. Potential energy = Joules 8. Apply the following settings for the simulation to answer the proceeded questions. a. Stop the simulation b. Click Reset then return skater buttons c. Adjust the coefcient of friction to one-eighth mark on the slide .U'PP" Physics Lab (Online Simulation) d. Open the Energy versus Time graph e. Run the simulation for 20 seconds 9. What are the energies at 12 seconds and 17 seconds a. at 12 seconds: K = U = Eth = b. at 17 seconds: K = U = Eth = 10. Calculate the change and total energies a. AK = AU = AEth = b. Total energy: AE = AK + AU + AEth = Part II: Double Well (Roller Coaster) Energy Skate Park (2.11) Q X File Tracks Help Tracks Reset Return Skater Choose Skater. Measuring Tape 5 Potential Energy Reference Grid Path Show Path Clear Energy Graphs W Show Pie Chart i with Thermal Bar Graph Energy vs. Position Energy vs. Time Location Space Moon Earth Jupiter Gravity 9.81 N/kg Space Earth Jupiter PE = 0 at this dotted line Clear Heat Track Friction > Edit Skater > Sim Speed Help! 1:39 PM - 4 4/2/2012 1. Click Reset and return skater buttons and put the reference line as shown above. Measure height of each control point from the reference line and calculate the potential (U), kinetic (K), and total (E) energies. a. At point 1: h1 = m. K= E1 = b. At point 2: h2 = m. U2 = K, = E2 = c. At point 3: h3 = m. U; = K; = E3 = d. At point 4: h4 = m. U4 = KA = EA 2. Calculate the speeds at control points 3 and 4 using the kinetic energies result you calculated in the previous step. a. The skaters speed at point 3: V3 = m/s b. The skaters speed at point 4: V4 = m/s C . 3. Now open the Energy vs position graph and read the potential (U), kinetic(K), and total (E) energies at the control pointsPhysics Lab (Online Simulation) a. At point 1: U1 = J K] = J E1 = I b. At point 2: U2 = J K2 = J E; J C. At point 3. U3: J K3 = J E3 = J c]. Atpoint4: U4= J K4: J E4: J 4. Calculate the heights at each of the control points using the information from step 3. a. h]: gm, 1]; 111, hr m, h4 m, h5 m. 5. How the shape of potential and kinetic energies do related to the shape of the track? a. Potential energy to the track: b. Kinetic energy to the track: 6. If you change the location to Moon instead of Earth, will the shape the energies change? If not, what is changed? 7. Apply the following settings for the simulation to answer the proceeded questions. a. Stop the simulation b. Click Reset then return skater buttons c. Adjust the coefcient of friction to one-eighth mark on the slide (1. Open the Energy versus Time graph e. Run the simulation for 20 seconds 8. What are the energies at 9 seconds and 16 seconds a at the 9ttl second: K J U J Em = J b. at the 16'h second: K = J U = J Em = J 9. Calculate the change and total energies. Em is thermal energy 3. AK = J AU = J AEu1 = J b. Total energy: AB = AK + AU + AE1 = J Follow up Questions: 1. At the highest point kinetic energy is zero 1' maximum while the potential energy is zero /maximum. 2. At the lowest point kinetic energy is zero / maximum while potential energy is zero /maximum. 3. Mass affects / does not affect the conservation of energy. 4. How much potential energy does the 60. kg skater have before she starts her ride, 12 m above the ground? 5. How much kinetic energy does a 60.0 kg skater have traveling with a velocity of 4 m/s? 6. How fast must a 20. kg skater travel to have a kinetic energy of 360 Joules? 7. How high must a 2.0 kg basketball be thrown so it has a potential energy of 160 J? 8. How fast must the 2.0 kg basketball be thrown upward to achieve the same 160 J? 9. If a 75kg skater starts his skate at 8.0m, at his lowest point, he will have a velocity of 10. In the above question, all the potential energy became kinetic energy. How much work was done