This is my first slide about center of gravity and line of gravity

1. LINE OF GRAVITY
Dr. Mottakin Ahmed
Sports officer
Government college
Silwani,Raisen (M.P.)

2. Centre of Gravity
This is an imaginary point
in a body at which the sum
of partial gravity forces of
all the body parts acts.
According to Newton’s law
of gravitation, every
particle is attracted towards
earth with a force.

3. The resultant of all the
partial forces acted at
one point, which is
called centre of gravity.
It is commonly
abbreviated as C.G.
It is the point where
body can be balanced

4.  In case of symmetrical
bodies, the centre of gravity
is in the geometrical centre
of the body.
 IF the density of the body is
not uniform or shape is not
like geometrically
symmetrical then the centre
of gravity will be towards
the heavier side of the body.

5.  In multisegmented
structures such as human
body, the centre of gravity
does not remain at any fixed
position but it position
changes depending upon the
relative position of different
body segment.
 It may lie even out side the
Physical limit of the body.

6.  The center of gravity of a body
is sometimes described as its
balance point or that point about
which a body would balance
without a tendency to rotate.
 For this reason, the center of
gravity is often identified as the
point where all the weight of the
body or object is concentrated.
 More accurately, it is the point
where the weight of the body
may be said to act.

7. LINE OF GRAVITY
 The line of gravity is an imaginary
vertical line from the centre of gravity
to the ground or surface the object or
person is on.
 The line of gravity is an imaginary
vertical line from the centre of gravity
to the ground or surface the object or
person is on.
 The location of this line in relation to
the base of support has a huge
influence on balance and stability.

8. The closer the line of gravity is
to the centre of the base of
support the better balanced a
person is in this position.
 lower centre of gravity means
better balance and stability.
a shorter line of gravity
between the centre of gravity
and the ground also means
better balance and stability.

9. An imaginary line that extends
vertically through the center
of gravity, through the base of
support when the body is in
balance and outside of the
base of support when the
body is out of balance.

10. • The ability to locate the center
of gravity of a body is based
on the knowledge of what it
takes for a system to be
balanced, or in equilibrium.
Two conditions must be met:
1. All the linear forces acting on
the body must be balanced.
2. All the rotary forces (torques)
must be balanced.

11. Factor affecting location of center of gravity

12. C.G. is directly proportional to he
area of the base on which the body
rests
Wider the area of the
base, higher the stability
and vice versa.
In sports like Judo,
wrestling, boxing,
weight lifting, the feet
should be kept wide
apart to increase the
area of the base

13. Implications
During the handstand on
one hand the finger
should be well spread.
In executing a hand stand
in gymnastic, the hand
should be kept shoulder
with apart to increase the
area of the base and to
have better balance

14. The higher the centre of gravity , the
less will be stability and vice versa
In multisegmented structure having a multiple degree
of freedom.
E.g. Human body where the position of centre of
gravity can be raised or lowered by changing the
relative position of various body segments, the
proper positioning of the body parts is important.

15. Implication
 While catching the heavy object or a fast moving
ball, like receiving a cricket ball, flexion of the
knee is recommended.
 To stop quickly in game situation , as in football,
hockey basketball, the center of gravity of the
body should be lowered by flexing the knees
with a simultaneous increases in area of base.
 In hammer throwing, after the release of the
hammer, the body should be lowered to acquire
a stable position to avoid crossing throwing
circle.

16. The centre must fall within the area
of base within the area of base
• The moment the center of gravity falls outside the
area of the base.
• The moment the center of gravity fall outside the
area of base, there will be threat to stability.

17. Implications
In pyramid making, the
common centre of gravity of
the system must fall within the
area of the base.
While walking on rope,
movements of the arms
should be so coordinated that
the centre of gravity fall
within the narrow base made
by the feet

18. C.G.is directly proportional to the
weight of the body
The greater the weight of the
body the higher is the C.G.
& stability and vice versa.
This is one of the reasons
that in sports, which involve
physical contact like judo,
wrestling, and boxing, there
are weight categories

19. Segmentation
• There is maximum stability in multisegmented system
or of a body when mass centre of all the weight
bearing segments lie in vertical line as far as possible.
• Maximally close to the common line of gravity which
is centered above the base of support.

20. Implication
• In gymnastics, in
executing a handsand or
headstand, if body is
kept straight, it will be
more stable as well as
economical i.e. less
energy demand

21. The shape of the base of the
support
The area of base should
be increased in the
direction of the on
coming imbalancing force.
When the direction of the
imbalancing force is
unpredictable or the
direction of the
movement is not known,
a diagonal stance should
be proffered.

22. Implication
While catching the ball, the rea of the base should be
increased in the direction of the on coming ball.
Team games, boxing, wrestling a diagonal stance is
more favorable.

23. Horizontal distance between C.G.
and limit of base in that direction.
Stability in a given direction is
directly proportional to the
horizontal distance between the
C.G. and limits of the base in
that direction. The larger is the
horizontal distance, the higher
will be the stability
Example: The centre of gravity is
kept in forward direction by
shifting the body weight in
forward direction.

24. Implication
While taking a start in
swimming or sprinting, the
body position should be such
that the centre of gravity is as
close to the front edge of the
area of base as possible.
In wrestling Judo, if pull is
exerted from the front,
keeping the centre of gravity
to the rear is helpful to
maintain position

25. Summary
To maintain balance, the centre of gravity must be kept
within the area of base.
To stop Quickly, drop the centre of gravity as low as
possible and increase the area of base with a simultaneous
shift of the centre of gravity (body weight) in the
intended direction of motion.
To change direction, first lower the centre of gravity and
increase the area of the with a simultaneous shift of
centre of gravity is near to the limit of the area of the
base.

26. While making pass in team games, the ball should be
delivered to the teammate in the direction in which his or
her centre of gravity is near to the limit of area f the base.
When the direction of imbalancing force is known then
the area of the base should be widened in the direction of
the on coming force.
When the surface are slippery or there is insufficient
friction, the area of the base should not increased more
than width of the pelvis.