Fan chair
From WikiDemos
Fan Chair is a simple demo that shows pushing against air can generate forces. This idea is important for flight and air resistance.
Contents |
Materials
- One office swivel chair
- Two standing office fans
- Pipe (the diameter is dependent upon the size of the fan post)
- Extension cord
Setup
Once you have the fans, remove their feet. This should cause them to end with the metal post of the stand. Find a piece of pipe that fits outside (although I assume inside could work as well) of the metal post. Attach this pipe to the bottom of the swivel chair. Now you can slide the fan legs into each side of this pipe to support them with one sticking out each side of the chair. Spin one fan so it is pointed forward and the other so it is pointed backwards. Now have someone sit in the chair and hold the fans in place if they are not otherwise snapped in. Plug the fans into the extension cord near the base of the chair. Now when the fans are turned on, the chair and rider will spin until they are stopped, making sure to do this before the cords are too tangled.
Explanation
When the fans are turned on, one fan pushes the air forward while the other pushes the air backwards because of the different directions they are pointed. Newton's third law stated that each action has an equal but opposite reaction. These reactions push against the chair and cause it to begin to rotate. Slowly, it picks up speed. This pushing against the air to create forces can explain flight and air resistance. By pushing against the air, the plane generates lift. Many people claim planes fly because of Bernoulli's Principle but the plane still needs something to push against or it would disprove Newton's third law. Air resistance is a form of friction caused by rubbing or pushing against the air. This showed that pushing can speed you up and likewise, if spinning and reversing the fans, can slow you down.
Health & Safety
- Don't let the cords get too tangled
- This experiment involves power from the mains
- Make sure nothing will get hit by the fans when the chair rotates
Improvements
- Adding an electrical slip ring to allow the chair to continue to rotate.
- Using fans that run off of 12 volts would make it safer and might make the slip rings easier to build.
- Modify the fans to clip into the pipe so the rider doesn't have to hold them.
- Add streamers to the fans to show the movement of air.
