March 2008

## Blowin' in the wind: solution

In last issue's Outer space we developed a formula for the power output per unit time of a windmill:The answer lies in understanding that the average speed is not a good guide. If, for example, the wind speed was for half of the time unit and 0 for the other half, then we would get an output approximately equal to

## Comments

## rotation speed of windmill blade

If forward wind speeds are 4, 6, 8, 10 m/sec What is the tip speed of a 40m blade at each input rate? (formula?)