problem 3.9, engineering fluid mechanics 9th edition SI version apply the grid m
ID: 1861231 • Letter: P
Question
problem 3.9, engineering fluid mechanics 9th edition SI version
apply the grid method to each situation:
a)what is the change in air pressure in pascals between the floor and the ceiling of a room with walls that are 2.5 m high.
b) a diver in the ocean (S=1.03) records a pressure of 1520mm-Hg on her depth gage. how deep is she?
c)A hiker starts a hike at an elevation where the air pressure is 10m-H2O, and ascends 3.7m to a mountain summit. assuuming the density of air is constant, what is the pressure in m-H2O at the summit
d) Lake pend Oreille, in northern Idaho, is one of the deepest lakes in the world, with a depth of 350 m in some locations. this lake is used as a test facility for submarines. what is the maximum pressure that a submarine could experience in this lake.
e) a 60 m tall standpipe (a standpipe isa vertical pipe that is filled with water and open to the atmosphere) is used to supply water for fire fighting. what is the maximum pressure in the standpipe?
Explanation / Answer
a) pressure difference = rho*g*h = 1.23*9.81*2.5 = 30.166 Pa b) S=1.03 density, rho = S*1000 = 1030 kg/m3 pressure=rho*g*h h=pressure/(rho*g) = 1.520*13600*9.81/(1030*9.81) = 20.07 m c) pressure = 10*1000*9.81 = 98100 Pa increase in pressure due to ascend = 3.7*1.23*9.81 = 44.645 Pa total pressure at summit = 98100+44.645 = 98144.645 Pa in term of height of water, pressure = 98144.645/(1000*9.81) = 10.004551 m of H2O d) maximum pressure will be experienced at maximum depth of lake i.e. at 350m maximum pressure = 1000*9.81*350 = 3433500 Pa e) maximum pressure will be experienced at the lowest point = 60*1000*9.81 = 588600 Pa
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