Windmills

1.I made two rotors and the only difference was how they were connected to the dowel. One was connected by three vertically slanted craft sticks on the dowel, the other was three craft sticks connected to two pyramids that surrounded the dowel. The one with the two pyramids had a shorter base then the three craft sticks directly connected to the dowel, since I had cut the craft sticks. The pyramid windmill worked better, probably because it had more room for the string to move by itself, which meant I had to touch it (and cause friction) less often.
2.The difference between most of the turbines and the most powerful one was that the most powerful one had long and thin turbines and most of the others were short and wide. The most powerful one also looked like it had sturdy turbines, unlike the other turbines that were long and thin, which looked flexible. If the turbines were flexible, the wind wouldn't be able to apply as much pressure.
3.Some limitations to my design could be that the turbines aren't slanted. Because of the turbines not being slanted very much, the wind hit the turbines at an equal force, not allowing for rotation to happen. Also, with my triangle rotor, I think one of my turbines was heavier then the others, so that it wasn't able to spin easily.
4.An airplane uses air pressure by making the wind going over the top of the wing go faster then the wind going under the wing, causing lift and pushing up on the wings, which lifts the airplane into the sky. A turbine uses air pressure by having the air pressure slide by the slanted wing, which means when the air pushes off to one side so that the air can continue it's forward momentum. When the air does this, it pushes on the wing so that the wing spins in the other direction, causing rotation.
5.It is necessary to put the turbine wings at a slant so that the air doesn't evenly hit the wings, because if the air hit the wings evenly, there would be no rotation.
6.A turbine and a sail on a sailboat both use air pressure to push the sail or wing forward. When a sail is used going with the wind, the wind is pushing against the sail, which moves it forward. When the sailboat is going against the wind, what happens is the sail goes at a back and forth slant. When the sail is at a slant, an area of low pressure is made at the front side of the sail because of the wind going to the back of the sail, according to Newton's Third Law. This creates an opposite push. This happens with a wind turbine also.
                               time                       height (meters)                          mass (grams)
triangle (test 1)        2:28                          0.86                                        29.55
triangle (test 2)        1:36                          0.67                                        35.58
slant                        0:00                          1.10                                         0