Mechanical Engineering Principles

244 MECHANICAL ENGINEERING PRINCIPLES

surface of the water, what is the value of

its buoyancy? [78.59 MN]

3. A barge of length 20 m and of width 5 m
   floats on an even keel at a depth of 2 m.
   What is the value of its buoyancy?
   [2 MN]


4. An inclining experiment is carried out on
   the barge of Problem 3 where a mass
   of 20 kg is moved transversely across
   the deck by a distance of 2.2 m. The
   resulting angle of keel is 0.8°. Determine
   the metacentric height,GM.
   [0.155 m]


5. Determine the value of the radius of cur-
   vature of the centre of buoyancy, namely,
   BM, for the barge of Problems 3 and 4,
   and hence the position of the centre of
   gravity above the keel,KG.
   [2.026 m]


6. If the submarine of Problem 2 floats so
   that its top is 2 m above the water, deter-
   mine the radius of curvature of the centre
   of buoyancy,BM. [0.633 m]

Exercise 112 Short answer questions on

hydrostatics

1. Define pressure.


2. State the unit of pressure.


3. Define a fluid.


4. State the four basic factors governing the
   pressure in fluids.


5. Write down a formula for determining
   the pressure at any point in a fluid in
   symbols, defining each of the symbols
   and giving their units.


6. What is meant by atmospheric pressure?


7. State the approximate value of atmo-
   spheric pressure.


8. State what is meant by gauge pressure.


9. State what is meant by absolute pressure.


10. State the relationship between absolute,
    gauge and atmospheric pressures.


11. State Archimedes’ principle.


12. Name four pressure measuring devices.


13. Standard atmospheric pressure is
    101325 Pa. State this pressure in mil-
    libars.


14. Briefly describe how a barometer oper-
    ates.


15. State the advantage of a Fortin barome-
    ter over a simple barometer.


16. What is the main disadvantage of a
    Fortin barometer?


17. Briefly describe an aneroid barometer.


18. What is a vacuum gauge?


19. Briefly describe the principle of opera-
    tion of a U-tube manometer.


20. When would an inclined manometer be
    used in preference to a U-tube manome-
    ter?


21. Briefly describe the principle of opera-
    tion of a Bourdon pressure gauge.


22. What is a ‘dead weight tester’?


23. What is a Pirani gauge?


24. What is a McLeod gauge used for?


25. What is buoyancy?


26. What does the abbreviationBMmean?


27. What does the abbreviationGMmean?


28. Define BM in terms of the second
    moment of areaI of the water plane,
    and the displaced volumeVof a vessel.


29. What is the primary purpose of a ship’s
    inclining experiment?

Exercise 113 Multi-choice questions on

hydrostatics (Answers on

page 285)

1. A force of 50 N acts uniformly over and
   at right angles to a surface. When the