If you buy a car from a dealership you must be 19 so you can sign by yourself. Legal age to sign is 19. That might not go for some others like personal sellers or trades and etc. If you are asking minimum age for buying a car, it doesn't matter. Cars are property just like a stick of gum is.
The speed of the tips of the windmill blades should be about 5 times the speed of the wind. For a 10 m/s wind (about 20 mph, more or less), the tips move at 50 m/s. If the windmill has a large diameter, then 20 RPM is adequate, but if the diameter is small, a high RPM is required.he tip speed of the windmill blades is typically 5 times the wind speed. That is, in a ten-mph wind, the tip of the blades moves at 50 mph. (Think of the neighborhood kids getting into mischief.). 4. Ideally, you should have two or three blades.
Most large turbines produce their maximum power at wind speeds around 15 meters per second (33 mph). Considering steady wind speeds, it's the diameter of the rotor that determines how much energy a turbine can generate.Keep in mind that as a rotor diameter increases, the height of the tower increases as well, which means more access to faster winds.At 33 mph, most large turbines generate their rated power capacity, and at 45 mph (20 meters per second), most large turbines shut down.o calculate the amount of power a turbine can actually generate from the wind, you need to know the wind speed at the turbine site and the turbine power rating.