Transcript Slide 1

THIS PROJECT IS DONE BY:
VIJAY ANAND (X STD)
UNDER THE GUIDANCE OF :
MR.K.V. RAJESH (PHYSICS)
1. LAW OF FLOATATION
2. STABILITY OF A FLOATING BODIES
3. STABILITY AND METACENTRE OF A SHIP
4. EXPERIMENTAL DETERMINATION OF THE METACENTRIC
HEIGHT OF A SHIP.
5. PLIMSOLL LINE
6. HYDROMETER
1. The weight of the floating is equal to the weight of the
liquid displaced by it.
2. The centre of gravity of the floating body and the centre
of gravity of the liquid displaced are in the same vertical
line.
STABILITY OF FLOATING BODIES:
The equilibrium of a freely floating body is
said to be Stable , if on being slightly
displaced, the body returns To the original
equilibrium position.
Consider a floating body in
equilibrium.G is the centre of gravity of
the floating body and B is The center of
buoyancy . The line BG is vertical .
When the floating body is slightly displaced C is the new
center Of buoyancy. The vertical line through C meets the
original Vertical line BG at M.M is called the Hydrostatics.
` Metacenter’ of the floating body.
GM is
called the metacentric
height. The weight Of the body W
acts vertically downwards Through
G. The up thrust of value W acts
Vertically upwards through C.If the
metacenter Is above G, the couple
due to the forces at G and C is the
anticlock wise and brings the
floating body Back to its original
position. Hence in this case the
Equilibrium is stable. But if M lies
below G, the couple due to the
forces at G.
And C is clock-wise and
the couple tends to turn
the body away from the
equilibrium position.
Hence this equilibrium
is unstable .
body to be in stable equilibrium , the
Metacenter must be always above
the center of gravity of the body.
Note:
In the case of a sphere
floating in a Liquid , a tilt one way or
other does not change The shape of
the displaced liquid. Hence M
Coincides with G all the time .
Therefore , it is said to be in neutral
equilibrium and it continues to float
in all positions.
EXPERIMENTAL DETERMINATION OF THE
METACENTRIC
HEIGHT OF A SHIP.
The weight of the ship W is
determined By the displaced method.
Two identical Boats are attached one
on each side of The ship. In A and B
represent the boats At a distance l
apart on the deck. Filling A and B
alternately with water is Equivalent to
moving a known weight W from A and
B across the deck. Filling The boat B
with the same mass of water As in A ,
turns the ship through an angle ⍬. The
tilt ⍬ is determined by means Of a
plumb line suspended in the ship.
PLIMSOLL LINE
In 1876, Samuel Plimsoll took up the
matter and Suggested that compulsory load
lines called plimsoll Lines be introduced. These
lines were drawn on the side of every ship for
safe loading. The line for tropical fresh water
(lowest density) is at the top and That for the
north Atlantic seas is at the bottom (highest
density being very cold). A ship will be loaded
till it sinks to the appropriate line. Then
whatever its destination it will Float at the safe
level.
HYDROMETER
A hydrometer is an instrument which works on the
Principle that when a body floats in any liquid the weight
of the floating body is equal to the weight of the liquid
displaced.
A hydrometer is used to find the specific gravity of
a liquid. There are two type of hydrometers,
(1) The variable immersion hydrometer and
(2) The constant immersion hydrometer.
VARIABLE IMMERSION HYDROMETER
In
the variable immersion hydrometer, the
weight of the hydrometer is kept constant but
the depth of immersion varies depending on the
density of the liquid in which it is floated.
CONSTANT IMMERSION HYDROMETER
In
the constant immersion hydrometer, the
depth of the hydrometer is kept constant where
as the weight of the hydrometer is changed to
make it float to the same depth.
COMMON HYDROMETER
A common hydrometer consists
of a uniform glass stem which ends in
a broader glass tube. Below this is
bulb containing mercury or lead shots
to make it float vertically. The
hydrometer sinks to different depths in
different
liquids
And
deeper
immersion occurs in Lighter liquids.
There are two sets of hydrometers
having different ranges of specific
gravities. One for liquids Lighter then
water and the other for Liquids heavier
then water.