In the far west states of the country, one can find wind farms with wind turbines that turn in response to a force of high-speed air resistance, r = ½drhoav2. the power available is p = rv = ½drhoπr2v3, where v is the wind speed and we have assumed a circular face for the wind turbine of radius r. take the drag coefficient d = 1.00 and the density of air as 1.20 kg/m3.(a) for a wind turbine having r = 1.30 m, calculate the power available (in kw) for a velocity of v = 8.40 m/s.(b) for a wind turbine having r = 1.30 m, calculate the power available (in kw) for a velocity of v = 25.5 m/s.

The frequency of a tuning fork can be found by the method shown. a long tube open at both ends is submerged in a beaker of water, and the vibrating tuning fork is placed near the top of the tube. the length l of the air column is adjusted by moving the tube vertically. the sound waves generated by the fork are reinforced when the length of the air column corresponds to one of the resonant frequencies of the tube. the smallest value for l for which a peak occurs in sound intensity is 7 cm. l what is the frequency of the tuning fork? the speed of sound in air is 345 m/s. answer in units of hz