HW_SET_2.soln

# HW_SET_2.soln - 2.45 Determine the gage pressure at point A...

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2.45 Determine the gage pressure at point A in Fig. P2.45, in pascals. Is it higher or lower than Patmosphere? Solution: Take 9790 N m 3 for water and 133100 N m 3 for mercury. Write the hydrostatic formula between the atmosphere and point A: atm p (0.85)(9790)(0.4 m) A (133100)(0.15 m) (12)(0.30 m) (9790)(0.45 m) p ,  Fig. P2.45 Aa t m or: p p 12200 Pa . Ans  12200 Pa (vacuum)

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98 Solutions Manual Fluid Mechanics, Fifth Edition P2.48 The system in Fig. P2.49 is open to 1 atm on the right side. ( a ) If L = 120 cm, what is the air pressure in container A? ( b ) Conversely, if p A = 135 kPa, what is the length L ? Solution : ( a ) The vertical elevation of the water surface in the slanted tube is (1.2m)(sin55 ) = 0.983 m. Then the pressure at the 18-cm level of the water, point D, is Going up from D to C in air is negligible, less than 2 Pa. Thus p C p D = 109200 Pa. change, then jump across the mercury U-tube and go up to point C with a decrease: Going down from point C to the level of point B increases the pressure in mercury: This is the answer, since again it is negligible to go up to point A in low-density air. ( b ) Given p A = 135 kPa, go down from point A to point B with negligible air-pressure Once again, p C p D 112400 Pa, jump across the water and then go up to the surface: A Air 35 L C D 32 cm Fig. P2.48 B 18 cm 15 cm z = 0 Mercury Water Pa m m N Pa z p p water atm D 109200 ) 18 . 0 983 . 0 )( 9790 ( 101350 3 ) .( 3 a m Pa z p p C B mercury B C 112400 ) 15 . 0 32 . 0 )( 133100 ( 135000 ) 15 . 0 32 . 0 )( 133100 ( 109200 Ans m N z p p B C mercury C B Pa 131800 ) .( 594 55 sin / 306 . 1 distance slanted the Then 306 . 1 for Solve 101350 ) 18 . 0 ( 9790 112400 b Ans m L m z Pa m z z p p surface surface water D atm m 1.
Chapter 2 Pressure Distribution in a Fluid 103 Solution: The three freebodies are shown below. Pressure on the side-walls balances the forces. In (a), downward side-pressure components help add to a light W. In (b) side pressures are horizontal. In (c) upward side pressure helps reduce a heavy W.

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## This note was uploaded on 10/12/2011 for the course CIVIL 2000 taught by Professor Dong during the Spring '11 term at Miami University.

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HW_SET_2.soln - 2.45 Determine the gage pressure at point A...

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