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.
Retarding blades do not suffer this problem as the airspeed at the tips is reduced, by virtue of the fact that the blades are travelling in the same direction as the airflow caused by flight. <br /> For example: Suppose the speed of Rotor Blade tip (helo in a hover) = 350mph. Speed of the Helicopter in flight = 150mph. Speed of Advancing Blade (in flight) = 350 + 150 = 500mph This simple calculation will determine the maximum speed of the helicopter. Most typical helicopters can only go about 150mph or maybe a little faster. Compound helicopters or the V-22 Tilt-Rotor can fly at over 200mph or even 300mph. The maximum airspeed of a helicopter is limited by the speed of the rotor blade.