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.
To the hub, the turbines are 229 ft. tall with 136 foot blades, meaning the height from the base to the tip the blade is 365 ft. The bases of the turbines are 11-16 feet in diameter and the foundations, which run 30 ft, into the ground, are 15.6 ft across. Each wind turbine weighs roughly 1450 tons. How do they work? Wind Turbines operate on a simple principle. The energy in the wind turns two or three propeller-like blades around a rotor. The rotor is connected to the main shaft, which spins a generator to create electricity. How fast do the blades turn? At the optimum wind speed of 25-35 mph, the blades will rotate at 14 rpm. That gives them a speed of 105 mph at the tip. How much electricity do they produce? Each turbine produces about 2,000,000 kilowatt hours (kwh) per year, enough energy to power as many as 500 typical homes at 12,000 kwh per year. How strong do the winds have to blow for the blades to rotate? Wind turbines start operating at wind speeds of around 8 mph and reach a maximum power output at around 33 mph. When there is not enough wind to turn the blades, or when there is too much wind the turbines shut down.