phet.colorado.edu/en/simulations/pendulum-lab.

III. The Pendulum Drop:
→ Click the “Energy” tab.
→ Select Slow at the bottom for speed.
→ Now use the phet to answer the following questions below.

6. Pause the simulation and raise the Blue Item up to 90°. What energy type is at its highest and why?
7. Play the simulation. Describe where the Blue Item is when it has reached its highest kinetic energy and what happens to the energy of the item as it gains height again.
8. Continue to play the simulation. This simulation will go on and on for eternity if we let it. This simulation is in what we call a Closed System. We are only looking at the variables we want to in this simulation. In the Real World (Open System), if we had a Pendulum like this, it would eventually stop. Explain why it would stop in the Real World.

6. The potential energy is at its highest when the blue item is raised up to 90° because it has the highest position above the ground. Potential energy is dependent on the height an object is above the ground.

7. The blue item reaches its highest kinetic energy when it is at the lowest point of swinging, which is at the bottom of its arc. As it gains height again, the kinetic energy decreases and gets converted into potential energy.

8. In the real world, a pendulum would eventually stop swinging due to the presence of air resistance and friction. As the pendulum swings back and forth, it loses small amounts of energy to air resistance and friction with the pivot point. This energy loss gradually slows down the pendulum until it eventually comes to a stop.

6. When the Blue Item is raised up to 90°, its potential energy is at its highest. This is because potential energy is dependent on the height of an object and at 90°, the Blue Item is at its maximum height.

7. When the Blue Item has reached its highest kinetic energy, it is at the bottom of its swing. At this point, the Blue Item has converted all of its potential energy to kinetic energy. As it gains height again, the kinetic energy of the Blue Item decreases, and the potential energy increases.

8. In the real world, a pendulum like this would eventually stop due to the presence of external factors such as friction and air resistance. These external forces would gradually slow down the pendulum, converting its kinetic energy into other forms such as heat. This loss of energy over time would eventually cause the pendulum to come to a stop.