PHYS 1415 Lab-03: Conservation of Energy Objectives: . To verify the conservation of mechanical energy by determining the relationship between kinetic energy and potential energy. Conservation of energy: The law of conservation of energy tells us that we can never create or destroy energy, but we can change its form. In this lab, we will look at the conversion of energy between gravitational-potential energy, work, and kinetic (or moving) energy. 1. Open PhET simulation Energy Skate Park: Basics (https://phet.colorado.edu/en/simulation/energy-skate-park-basics). This simulation allows you to explore the motion and energetics of a skater riding along a track. 2. Click on "Intro" to get started. 0 A t5 https/pher Energy Pie Chart Bar Graph Grid Speed Small Mass Large Potential Therma meters 1. Slow Motion Restart Skater Energy Skate Park: Basics PhET 3. You can click and drag the skater to any location and release the skater from rest. Watch the skater skate up and down the track. 4. Click on the "Bar Graph" to see the relative magnitudes of the kinetic, potential, thermal, and total energies as a function of the skater's position. You can select "Slow Motion" below the track for a more accurate observation. 5. Play around with the simulation. Click on the "Reset" button before answering the questions. Activity-1 Question-1: How does the skater's kinetic energy change as he moves down the ramp? Question-2: How does the skater's kinetic energy change as he moves up the ramp? 1Question-3: How does the skater's potential energy change as he moves down the ramp? Question-4: How does the skater's potential energy change as he moves up the ramp? Question-5: How does the skater's total energy change as he moves down the ramp? Question-6: How does the skater's total energy change as he moves up the ramp? Because we are ignoring friction, no thermal energy is generated and the total energy is the mechanical energy, the kinetic energy plus the potential energy. E : K + U. Question-7: As the skater is skating back and forth, the total energy of the skater is Ignoring friction, the total energy of the skater is conserved. This means that the kinetic plus potential energy at one location, say E1 = K1 + U1, must be equal to the kinetic plus potential energy at a different location, say E2 = K2 + U2. This is the principle of conservation energy and can be expressed as E = E2. Since the energy is conserved, the change in the kinetic energy is equal to the negative of the change in the potential energy: K2 K1 2 (U2 U1). Activity-2 At the bottom of the simulation window, click on \"Playground\". For this part of the activity, you should have the \"Friction\" slider set to none, which means no thermal energy is generated. Select the \"Show Grid\" option. Then, add a track by clicking and dragging on a new track (the shape with three C] Plecharl . C] Bar Graph I2 Grid '_--_-_'h 'i'-\\-_-_U 11-- ' In] Energy Shale Park Basms circles in the bottom left of the window) and placing it near the skater. You can then click and drag on individual circles to stretch and/or bend the track and make it look as shown below. The bottom of the track should be 1 m above the ground, and both ends of the track should be at a height of 7 m. Place the skater on the track 7 m above the ground and look at the resulting motion and the Bar graph showing the energetics. Assume the mass of the skater is 75.0 kg and that the acceleration of gravity g = 10 m/s2. Important Formula: Kinetic Energy K = 1/2mi72 Potential Energy U = mgh Question-8: How much potential energy does he have at 7.0m? Question-9: How much kinetic energy at 0.0m? Question 10: A 20.0 kg skater that starts his skate 10m high (on the earth) would have a potential energy of and a kinetic energy of before his skate. At the lowest point, the skater would have a potential energy of and a kinetic energy of . (hint: use the important formula for potential energy) Complete the table of Kinetic and Potential Energies: use g = 10. m/s2 (1/2 pt each) Mass of skater m Height h Velocity v Kinetic Energy K Potential Energy U (kg) (in m) (in m/s) (in Joules) (in Joules) 20. kg 14m 12 m/s 1. 2. 60. kg 0.0 m 3. 1470 J 4. 5.0 kg 9. 10. 160 J 850 J Conclusion: Question 11: At the highest point kinetic energy is zero / maximum while the potential energy is zero / maximum. Question 12: At the lowest point kinetic energy is zero / maximum while potential energy is zero / maximum. Question 13: Mass aects/ does no: aecr the conservation of energy