# Skateboarder inquiry investigation

```Skateboarder inquiry investigation
Part 1: Intro
1. Go to the following URL: https://phet.colorado.edu/sims/html/energy-skate-parkbasics/latest/energy-skate-park-basics_en.html
2. Click on intro
3. Check “Bar Graph” on the left.
4. Place the skater half way up the ramp. What happens to the energies?
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5. As the skater goes up and down the ramp, what happens to the kinetic and gravitational
potential energies?
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6. Draw an energy flow diagram to represent the transformation going on here.
7. What do you notice about the total energy? Which law helps us to understand this?
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8. What two ways could you increase the skater’s GPE?
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9. Give the skater the largest GPE possible. What does that do the skater’s KE when they reach
the lowest part of the ramp? Why is this?
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10. Use the “Grid” setting, assuming the skater has a mass of 60kg, calculate the largest GPE
they could have. Use the following equation: GPE = mass x force of gravity x height
 Force of gravity on earth is 9.81 m/s2
 The units of GPE given are Joules (J)
11. Assume all of the GPE from step 10 was transformed into KE as the skater reached their
lowest point. Use the following equation to calculate the fastest speed (velocity) the skater
could go: KE = &frac12; mass x velocity2

The equation can be rearranged to 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 = √

The units of velocity are m/s
2&times;𝐾𝐸
𝑚𝑎𝑠𝑠
Part 2 - Friction
1. Click on the friction tab
2. Place the skater half way up the ramp. Observe what happens differently this time.
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3. Why does this occur?
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4. Click on “Bar Graph” repeat step 2. What do you observe about the energies involved?
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5. Which energy/ies are useful?
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6. Which energy/ies are wasted?
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7. Using the grid again place the skater at 6m, with the friction set to “Lots”, what is the
highest point the skater returns to on the other side of the ramp? ________________
8. Again, assuming the skater is 60kg, calculate the GPE at the start height and end height.
 See step 10 from part 1
9. The initial GPE was the “input energy” and the end GPE was the “useful energy output”.
Calculate the efficiency of the ramp and skateboard using the following equation:
% 𝑒𝑛𝑒𝑟𝑔𝑦 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =
𝑢𝑠𝑒𝑓𝑢𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑜𝑢𝑡𝑝𝑢𝑡
𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑝𝑢𝑡
&times; 100
10. Calculate the % energy efficiency with the friction set at about half (hint: follow the steps 79).
Part 3: Playground
1. Using the playground tab, create a skate ramp. Sketch it below:
2. Turn the friction down to “None”. Test your ramp, does it work? Why / Why not? If not
modify it to work.
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3. Click the release skateboard button (right). Does your ramp still work?
Why / Why not? If not modify it to work.
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4. Increase your friction to about half way. Does your ramp still work? Why / Why not? If not
modify it to work.
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6. What are the major differences between your original ramp and final ramp
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7. Using the terms, gravity, GPE, KE, speed, friction, useful energy, wasted energy, heat energy,
sound energy, conservation of energy, explain why those changes were needed, and how
they allowed your final ramp to work.
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```