__Investigate the relationship between gravitational potential energy and kinetic energy in a closed system.__

__Activity 1:__

1. Choose the PhET skater from the “Choose Skater” tab in the java applet.

2. Pause the simulation.

3. Click on the “Energy Vs Position” tab.

4. Uncheck the total, thermal and kinetic boxes.

5. Click the “Play” button.

**Questions:**

1. From the graph, when is the gravitational potential energy the least? What is this value?

2. When is the gravitational potential energy the most? What is this value?

__Activity 2:__

1. Check the kinetic box and uncheck the gravitational potential box.

2. Reset the simulation.

**Questions:**

1. From the graph, when is the kinetic energy the least? What is this value?

2. When is the kinetic energy the most? What is this value?

__Activity 3:__

1. Uncheck the kinetic box and check the total box.

2. Restart the simulation.

**Questions:**

1. What is the total energy of the skater at all times?

2. What can you say about the total energy of the whole system?

__Activity 4:__

Change the skater to the other types of skaters and repeat the Activities 1 to 3. Complete the table below.

Skaters |
Min GPE/J |
Max GPE/J |
Min KE/J |
Max KE/J |
Total E/J |

PhET Skater |
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Star Skater |
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BullDog |

**Question 1:**

a. As the skater goes down the slope, what happens to the value of the gravitational potential energy?

b. At the same time, what happens to the value of the kinetic energy?

c. What can you conclude about the relationship of the gravitational potential energy to the kinetic energy?

**Question 2: Check every box and restart the simulation for the PhET skater.**

a. When is the gravitational potential energy the maximum?

b. When is the kinetic energy the minimum?

c. What can you say about the point where the gravitational potential energy is the maximum and the kinetic energy is the minimum?

d. What can you say about the point where the gravitational potential energy is the minimum and the kinetic energy is the maximum?

**Question 3: Change the location to the moon.**

Does the shape of the total energy curve remain the same as that of the earth?

**Question 4:**

How does this relate to the Conservation of Energy theory?