13–32e a fan with 24-in-diameter blades moves 2000 cfm (cubic feet per minute) of air at 70°f at sea level. determine (a) the force required to hold the fan and (b) the minimum power input required for the fan. choose a control volume sufficiently large to contain the fan, with the inlet sufficiently far upstream so that the gage pressure at the inlet is nearly zero. assume air approaches the fan through a large area with negligible velocity and air exits the fan with a uniform velocity at atmospheric pressure through an imaginary cylinder whose diameter is the fan blade diameter.