A cylindrical tank of water that is open to the air has a drainage plug located
ID: 1565887 • Letter: A
Question
A cylindrical tank of water that is open to the air has a drainage plug located distance d = 7.5 m below the water surface. The total depth of the water, h = 10.0 m (to bottom of the tank, which rests on level ground). Outside the tank, we have air at atmospheric pressure. The cylindrical tank has a diameter of 5.00 m. The plug has an area 4.0 cm^2 in with the water. It is held in place by friction with the sides of the hole. (a) Find the gauge pressure of the water at the level of the plug. (b) Find the friction force that is needed to keep the plug in place. (c) The plug is removed and water spurts out of the resulting hole at a speed of 12.1 m/s. How far away (horizontally) from the tank does the water go before it hits the ground?Explanation / Answer
(A) P_gauge = rho g d
= (1000) (9.8) (7.5)
= 73500 Pa
(B) F = P A
= (73500) (4 x 10^-4)
= 29.4 N
(C) height from ground = 10 - 7.5 = 2.5 m
time taken to reach the ground ,
2.5 = 0 + 9.8 t^2 / 2
t = 0.714 sec
D = v0 t
= (12.1) (0.714)
= 8.64 m