Download Center of Gravity

fskondhor School
Grade 8 Physics
CEruTRE
qF GRAVITY
Centre of gravituJ$ass'l of a body is the point about which the entire weight (mass) of
the
body seems to act.
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The centre of gravity may be regarded as the point of balance.
The centre of gravity of a body is in the same position as its centre of m'ass.
The centres of gravity of regular shaped objects are at their geometrical centre.
For a uniform ruler, C.G is at the centre and when supported at this point it balances
and when supported at any other point it topples.
Square
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Suspend the shape from a location near an edge. Drop p plumb line and mark
on the
object.
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Suspend the shape from another location net too close {o the first. Drop a plumb
tine
again and mark.
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The intersection of the two lines is the center of mass.
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Centre of gravity
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Poge 1
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Notei Term 2,
2O1?
fskondhor School
Grade B Physics
Topplinq
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A body states stable if the vertical line ihrough its centre of gravity falls within the
base.
"& A hody topples if ihe vertical
line tl'lrough the centre of gravity falls outside the base.
Centre of gravity
Weight (W)
Weight (W)
Stabilitv can be increased bv
,$. Lowering the centre of gravity.
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lncreasing the base area.
Racing cars have low centre of gravity and a wider wheel base for higher stability.
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Irlotes Term
2, 2Al2
fskondhar School
Grade
I
Physics
Stabilitv
Stability is the abitity of an object to regain its original position after it has been displaced
slightly.
There are three types of equilibrium
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Stable equilibrium
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Neutral equilibrium
Unstable equilibrium
Eleltessuitiuriue
A body is said to be in stable equilibrium if when slightly (isplaced and then released
it
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returns to its original position.
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A cylinder on its base is in stable equilibrium. The vertical line from the centre of gravity
falls inside the base and so, when the cylinder is displaced slightly to one side, it returns
to its original position.
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When the vertical line from the centre of gravity falls juSt outside the base, the body
topples over.
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Poge 3
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Notes Term 2, 2A1?
fskondhor School
U
Grade 8 Physics
ngtab [e equilibrilrs'n
A body is said to be in unsiable equilibrium if when slightly displaced and then released
moves further away from its previous position.
':" The cone is in unstable equilibrium
because when it is given a small displacement it
moves further away from its original position (it topples over). The vertical line from
the centre of gravity soon falls outside the base and tfte bottle topples over.
Centre
of
graviiy
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Weight (W)
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-FCentre of gravity
weight (w)
Neutral equilibrium
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A body is said to be in neutral equilibrium if it stays in its new position when displaced.
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The ball is in neutral equilibrium. When it is slightly displaced, it will stay in its
position. lts centre of gravity remains at the same height.
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Weight (W)
Weight (W)
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Page
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Notes Term 2, 2At2
fskondhor School
Grade B Physics
eentre of gravity
Expenif,nent
Aim:
To find the centre'of gravity of an irregurarly
shaped lamina
Materials reguired:
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lrregular lamina
Thread and a bob
Nail clamped in a stand
Diaqram:
nailclamped
in stand
lamina
centre of
gravity
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Plumb line
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Procedure:
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Make a hole 'A' on the lamina and hang it so that
it can swing freely on a nail
clamped in a stand.
lt comes to rest wrth its centre of gravity verticaily
berow A
To find the vertical line (plumb line), tie a thread
and a mass to the nailand mark its
position AD on the lamina
.
n Now, Centre of gravity is on the line AD
* Hang the lamina from another position C
* Repeat the procedure and mark the plumb line ag CE
+ Centre of gravity lies on the line CE
* centre of gravity of the irregular lamina is exactty at the point of intersection
of AD
and CE
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Poge 5
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Notes Term
2, ZOI?