1. UNIT ISHIP’S
2. Slayt 2When
an object is afloat,
it is acted upon by two
forces; the downward
force of gravity and the
upward force of buoyancy
3. Slayt 3Buoyancy
is the ability
of an object to float.
4. Slayt 4If an object is placed into water
and the weight of this object is
greater than the weight of an
equal volume of water, the
object will sink. It sinks
because the force of buoyancy
is less than the weight of the
5. Slayt 5However, if the weight of the
object is less than the
weight of an equal volume
of water, the object will float
6. Slayt 6Centre
of gravity is the point of
application of the gravitational
force on the ship.
7. Slayt 7Centre
of buoyancy is the
point of application of the
buoyancy force on a ship.
8. Slayt 8
9. Slayt 9When
cargo is loaded to one
side of a ship, there will be a
temporary shift in the centre of
gravity. Once the ship tilts to
one side, the centre of
buoyancy will also shift.
10. Slayt 10The
ship's centre of gravity
determines the ship's stability.
11. Slayt 11Stability may be defined as
the ability of a vessel to
return to her initial position
13. Positive stability - M above GM
14. Neutral stability - M and G in same positionG
15. Negative stability - M below GG
16. State that the following sentences true or false according to the text.1-Two
forces act upon the
object when it is afloat.
17. Slayt 172-The
centre of gravitational
force is centre of buoyancy.
18. Slayt 183-If ship inclines, the centre
of buoyancy changes.
19. Slayt 194-If M is below G, this means
that the ship is not stable.
20. SOME WORDSDeflection (n) - Deviation,
21. Slayt 21Equilibrium (n) - Balance
22. Slayt 22Incline (v) - To deviate from a
vertical position, to lean, to
23. Slayt 23Shift (v) - To change position or
24. Slayt 24Sink (v) - To fall down below the
surface of the water, to submerge
25. Slayt 25Stable (adj.) - Steady, fixed
26. Slayt 26Tilt (v) - To incline, to slope
27. B-Underline the true word or phrase in italics1-The
gravitational force is
upward / downward force.
28. Slayt 282-If
metacentre is above / below
centre of gravity , this ship will be
29. Slayt 293-When
the force of buoyancy is
less than the weight of the object,
it sinks / floats.