PHET Energy Skate Park Simulation Part 1: Observing Energy 1. Familiarize yourself with the simulation, play around as much as you want. 2. Select the "Intro" tab and hit the yellow reset button. 3. Check the pie chart, bar graph, and grid boxes. 4. Place the skater on the track, and observe. (The skater should be moving, if they aren't then you might need to hit the play button.) Question 1: Describe the four bars of the bar chart, what are they doing? Why is the thermal bar zero? 5. Try changing the skater mass, as well as the starting position. o Question 2: How do the skater mass and starting position change the way the bar graphs act? Do they change at all? 6. Switch to the "Friction" tab, and repeat steps 3-5. o Question 3: What effect does adding friction have on the graphs? Part 2: Conservation of Energy Hopefully you noticed that so long as mass and initial height are kept the same, the total energy will never change. This is the law of conservation of energy. 1. Select the "Friction" tab and reset. Mark the speed and grid checkboxes. 2. Pick and record a height that is easily measured via the grid lines. Drop the skater from this height (without having her hit the ramp). 3. Use slow motion and/or the frame by frame button to find the tick mark on the speed gauge just before she lands. o Question 4: (a)Use either 1D free fall kinematics or conservation of energy to compute the final velocity just before she lands (b) How much speed is each small/large tick mark worth on the speed gauge? (c) Does this computation require you to know time? 4. Place the skater at the same height as in step 2, but on the ramp. Drop her with the friction slider set to "None". o Question 5: (a) Is her speed the same at the bottom of the ramp as when you dropped her in steps 2 and 3? (b) What is this an example of? Show the energy computations. (c) What can you do to make her have a different speed at the bottom of the ramp?5. Place the skater at the same height as in step 2, but on the ramp. Drop her with the friction slider set to "Lots". o Question 6: (a) What is her new maximum height? (b) How much energy must have been lost to friction if she has a mass of 60kg? Part 3: The Loop 1. Navigate to the third tab called the "Playground" 2. Create a loop-the-loop scenario with a rather small (less than 5 m height) loop. 3. Measure and record the height of the loop. Note: You need to keep this height consistent for this part. 4. Set friction to "None". o Question 7: At what minimum starting height can our skater make it through the loop? 5. Set friction to about halfway. o Question 8: At what minimum starting height can our skater make it through the loop? 6. Set friction to "Lots" o Question 9: At what minimum starting height can our skater make it through the loop? Do these results make sense? Why? 7. Let's make a plot of the relationship between starting height and friction to determine the scaling of the friction. Keep the mass on the default setting. o Question 10: Using 5 distinct and constantly increasing friction values, make a bar graph of the necessary starting height to overcome the loop. What sort of fit does friction seem to make with height? 8. Repeat steps 4-6 with a different mass. o Question 11: Does changing mass affect at what minimum starting height can our skater make it through the loop? Why or why not