Page 225 - Schaum's Outline of Theory and Problems of Applied Physics

210 FLUIDS IN MOTION [CHAP. 17

17.7. Water comes out of a valve at the bottom of a tank at 20 ft/s. The height of water in the tank is
(a) 6.25 ft (c) 20 ft
(b) 12.5 ft (d) 25 ft

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17.8. Water flows through a pipe whose cross-sectional area is 50 cm into another pipe whose cross-sectional area is
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10 cm . Both pipes are horizontal. If the velocity of the water in the large pipe is 1.2 m/s, the velocity in the small
pipe is
(a) 0.24 m/s (c) 6.0 m/s
(b) 1.2 m/s (d) 30 m/s

17.9. Water flows through the small pipe of Question 17.8 at
(a) 0.6 L/s (c) 3.0 L/s
(b) 1.2 L/s (d) 6.0 L/s

17.10. If the gauge pressure in the large pipe of Question 17.8 is 200 kPa, the gauge pressure in the small pipe is
(a) 181 kPa (c) 183 kPa
(b) 182 kPa (d) 217 kPa

Supplementary Problems

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17.1. An airplane’s wings are designed to have a pressure difference of 0.4 lb/in. between their upper and lower surfaces.
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If the area of the wings is 300 ft , what is the design weight of the airplane when it is fully loaded?
17.2. A water tank is on the roof of an apartment house. A faucet is opened on the ground floor, 140 ft below the water
level in the tank, and there is no frictional resistance in the plumbing system. With what velocity will water emerge
from the faucet?

17.3. What gauge pressure is required in a fountain if the jet of water is to be (a) 20 ft high and (b) 20 m high?

17.4. Water leaves the nozzle of a hose at a velocity of 40 ft/s. (a) If the nozzle is held vertically, how high does the water
reach? (b) If the nozzle is held horizontally 5 ft above the ground, how far does the water stream go before striking
the ground?
17.5. Water emerges from a faucet 5 mm in diameter at 2 m/s. (a) If the pipe leading to the faucet is 3 cm in diameter, find
the water velocity in the pipe. (b) At what rate does water leave the faucet?
17.6. Water flows at a velocity of 5 m/s through a hose whose inner diameter is 20 mm. (a) What should the nozzle
diameter be for water to emerge at 15 m/s? (b) Find the rate of water through the hose in liters per minute. (c) Find
the force needed to hold the nozzle.

17.7. Water emerges from the 2-in.-diameter nozzle of a hose at the rate of 200 gal/min. Find the force with which the
nozzle must be held.

17.8. Water passes through a turbine at a rate of 3000 L/s. If the water enters the turbine at 7 m/s and leaves at 1.5 m/s,
find the average force exerted on the turbine blades.

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17.9. A pressure gauge in a water supply system reads 40 lb/in. when no water flows and 34 lb/in. when a tap is opened.
What is the flow velocity?
17.10. A tank of gasoline has a crack 1 mm wide and 5 cm long at its base. If the liquid level is 2 m above the base, find
the rate at which gasoline leaks out in cubic meters per second and liters per second.