1. QUESTIONS

2. Homework
Jack load 12.2kN
Gage pressure: 27.7kPa

3. SG = 0.8

4. Examples
Mercury manometer is connected to an air duct to measure its insice pressure. The manometer deflection is 15mm. Atmospheric pressure is 100kPa. Find the duct’s absolute pressure. Hg  = 13,600kg/m3.

7. Manometer
Liquid flow deflection large; manometer fluid can be Hg, SG = 13.6
Gas flow deflection small; manometer fluid SG <~ 0.9. Use inclined manometer

9. Example
Mott 3.71 Figure Gage fluid has a SG = 0.87 and L = 115mm.  = 15o. Find PA.

11. Fluid statics Liquid at rest: F = 0
Horizontal: equal in all directions
Horizontal: dependent on depth
Vertical: pressure prism
P = h

12. Hydrostatic forces Pressure prism Distributed forces Force → vector
Direction
Magnitude
Line of action: center of pressure

14. Fluid statics F = hcA magnitude
hcp = hc + (I/ hcA) center of pressure

16. Submerged surface location
Top edge at liquid surface
Top edge submerged
Pressurized surface –equivalent depth of fluid
Inclined surface
Curved surface

17. Example
A heavy car veers off the road into a lake. It settles upright on the bottom. The front car door is 1.2m high and 1m wide. The top of the door is 8m below the lake surface. What is the force holding the door closed? Can the driver open the door? What can he do to survive?

18. Example
A rectangular gate is installed in a vertical wall of a reservoir. Find the magnitude of the resultant force and the center of pressure. What is the force of each latch?

20. Example
The square gate is eccentrically pivoted so that it automatically opens at a certain value of h. What is that value in terms of l ?

22. Homework
A gate for the spillway holds water at a normal high level mark. The spillway crest elevation is ft. The gate span is 30 ft. What is the force on the two pins holding the gate in place?

24. Homework
The air above the liquid is at 40kPa. The SG of the liquid is The rectangular gate is 1.0m wide; y1 = 1.0m; and y2 = 3m. What force P is needed to hold gate in place?

26. Homework
The inclined wall is 4m wide. Find the magnitude of the resultant force and the center of pressure.

31. Centroid of compound area
Moment of compound area about any axis is equal to sum of the moments of its parts around the same axis
= (A1 x1 + A2 x2)/ AT

33. Assignment
Mott Chapters 3 & 4
Ch.4: 16,20,40,47

35. Images & examples References
Fluid Mechanics Fundamentals & Applications, 6th Edition, Cengel & Cimbala, McGraw Hill
Applied Fluid Mechanics, 6th Edition, Mott, Prentice Hall
Engineering Fluid Mechanics, 5th Edition Crowe, & Roberson, Wiley