Page 1
Constrains
Constrains: Condition or restrictions imposed on motion of
particle/particles
Motion of particle not always remains free but often is subjected to given
conditions.
A particle is bound to move along the
circumference of an ellipse in XZ plane.
At all position of the particle, it is bound
to obey the condition
+
=1
X
Z
Page 2
Constrains
Constrains: Condition or restrictions imposed on motion of
particle/particles
Motion of particle not always remains free but often is subjected to given
conditions.
A particle is bound to move along the
circumference of an ellipse in XZ plane.
At all position of the particle, it is bound
to obey the condition
+
=1
X
Z
Classification of constrains
? Non-holonomic constrains : Constrains which are not holonomic
Two types of constrains are there in this category
(i) Equations involving velocities:
, … ,
, … . ,
, = ,
(& those cannot be reduced to the holonomic form!).
(ii) Constraints as in-equalities,
An example,
, … . ,
, <
? Holonomic Constrains: Expressible in terms of equation involving
coordinates and time (may or may not present),
I,e.
, … .
, = ; where
are the instantaneous coordinates
In both type of constrains (holonomic/non-holonomic) time may or may not be
present explicitly.
Page 3
Constrains
Constrains: Condition or restrictions imposed on motion of
particle/particles
Motion of particle not always remains free but often is subjected to given
conditions.
A particle is bound to move along the
circumference of an ellipse in XZ plane.
At all position of the particle, it is bound
to obey the condition
+
=1
X
Z
Classification of constrains
? Non-holonomic constrains : Constrains which are not holonomic
Two types of constrains are there in this category
(i) Equations involving velocities:
, … ,
, … . ,
, = ,
(& those cannot be reduced to the holonomic form!).
(ii) Constraints as in-equalities,
An example,
, … . ,
, <
? Holonomic Constrains: Expressible in terms of equation involving
coordinates and time (may or may not present),
I,e.
, … .
, = ; where
are the instantaneous coordinates
In both type of constrains (holonomic/non-holonomic) time may or may not be
present explicitly.
Pendulum
Y
X
? s
+ "
= #
= #
- "
% ? One can not change independently,
any change in will automatically
change ".
&, ' ()*
+ independent due to presence of constrains
(, ")
Independent coordinates: If you fix all but one coordinate and still have
a continuous range of movement in the free coordinate.
If you fix "
.
, leaving
.
free, then there is no continuous range of
.
possible. In fact in this case there will not be any motion if you fix "
.
Page 4
Constrains
Constrains: Condition or restrictions imposed on motion of
particle/particles
Motion of particle not always remains free but often is subjected to given
conditions.
A particle is bound to move along the
circumference of an ellipse in XZ plane.
At all position of the particle, it is bound
to obey the condition
+
=1
X
Z
Classification of constrains
? Non-holonomic constrains : Constrains which are not holonomic
Two types of constrains are there in this category
(i) Equations involving velocities:
, … ,
, … . ,
, = ,
(& those cannot be reduced to the holonomic form!).
(ii) Constraints as in-equalities,
An example,
, … . ,
, <
? Holonomic Constrains: Expressible in terms of equation involving
coordinates and time (may or may not present),
I,e.
, … .
, = ; where
are the instantaneous coordinates
In both type of constrains (holonomic/non-holonomic) time may or may not be
present explicitly.
Pendulum
Y
X
? s
+ "
= #
= #
- "
% ? One can not change independently,
any change in will automatically
change ".
&, ' ()*
+ independent due to presence of constrains
(, ")
Independent coordinates: If you fix all but one coordinate and still have
a continuous range of movement in the free coordinate.
If you fix "
.
, leaving
.
free, then there is no continuous range of
.
possible. In fact in this case there will not be any motion if you fix "
.
Degree of Freedom &Generalized coordinate
Y
X
/
? If you choose / as the only coordinate, it
can represent entire motion of the bob in
XY plane
? In this problem, only one coordinate / is
sufficient which is sole independent
coordinate.
Degree of Freedom (DOF): no of independent coordinate required
to represent the entire motion = 3 × 2 34# -
. 2 4 =3-2=1
In this case no. of particle=1
No. of constrains =2 [
+ "
= #
and 5 = 0]
DOF =1; Generalized Coordinate= /
Page 5
Constrains
Constrains: Condition or restrictions imposed on motion of
particle/particles
Motion of particle not always remains free but often is subjected to given
conditions.
A particle is bound to move along the
circumference of an ellipse in XZ plane.
At all position of the particle, it is bound
to obey the condition
+
=1
X
Z
Classification of constrains
? Non-holonomic constrains : Constrains which are not holonomic
Two types of constrains are there in this category
(i) Equations involving velocities:
, … ,
, … . ,
, = ,
(& those cannot be reduced to the holonomic form!).
(ii) Constraints as in-equalities,
An example,
, … . ,
, <
? Holonomic Constrains: Expressible in terms of equation involving
coordinates and time (may or may not present),
I,e.
, … .
, = ; where
are the instantaneous coordinates
In both type of constrains (holonomic/non-holonomic) time may or may not be
present explicitly.
Pendulum
Y
X
? s
+ "
= #
= #
- "
% ? One can not change independently,
any change in will automatically
change ".
&, ' ()*
+ independent due to presence of constrains
(, ")
Independent coordinates: If you fix all but one coordinate and still have
a continuous range of movement in the free coordinate.
If you fix "
.
, leaving
.
free, then there is no continuous range of
.
possible. In fact in this case there will not be any motion if you fix "
.
Degree of Freedom &Generalized coordinate
Y
X
/
? If you choose / as the only coordinate, it
can represent entire motion of the bob in
XY plane
? In this problem, only one coordinate / is
sufficient which is sole independent
coordinate.
Degree of Freedom (DOF): no of independent coordinate required
to represent the entire motion = 3 × 2 34# -
. 2 4 =3-2=1
In this case no. of particle=1
No. of constrains =2 [
+ "
= #
and 5 = 0]
DOF =1; Generalized Coordinate= /
Degree’s of freedom
? Degree’s of freedom (DOF): No. of independent coordinates
required to completely specify the dynamics of particles/system
of particles is known as degree’s of freedom.
?Degree’s of freedom =
3 × . 2 34# - 7. 2 8#94 4
= 37 - :
Where
7= No. of particles
: =No. of constrains.
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