The figure below shows the top view of a sprinkler which rotates about axis c. W
ID: 1920960 • Letter: T
Question
The figure below shows the top view of a sprinkler which rotates about axis c. Water leaves the sprinkler at a velocity of 20 ft/sec, relative to the tip, A in the horizontal plane in which the arms would rotate. Compute the Force, F necessary to hold the arms in place. The nozzle @ A has a 1-inch diameter, and the tangential velocity at the inner radius, Vt1 = 0.
The figure below shows the top view of a sprinkler which rotates about axis c. Water leaves the sprinkler at a velocity of 20 ft/sec, relative to the tip, A in the horizontal plane in which the arms would rotate. Compute the Force, F necessary to hold the arms in place. The nozzle @ A has a 1-inch diameter, and the tangential velocity at the inner radius, Vt1 = 0.Explanation / Answer
impulse due to water = change in momentum = m*20ft/sec , mass is mass of water coming out in 1 sec
so Impulse = density *area*velocity * 20ft/sec = 62.4 * (pi*1*1/12*12*4) * 20 *20 = 136
so now we balance the torque
so 2*F*4 = 2*136*sin30 * 6
so F = 34*0.5*6 = 102 lb