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.
Every wind turbine has a range of wind speeds, typically around 30 to 55 mph, in which it will produce at its rated, or maximum, capacity. At slower wind speeds, the production falls off dramatically.ind turbines generate electrical energy when they are not shut down for maintenance, repair, or tours and the wind is between about 8 and 55 mph. Below a wind speed of around 30 mph, however, the amount of energy generated is very small. Wind turbines produce at or above their average rate around 40% of the time.