Semi-holonomic constraints (analytical mechanics)

In summary, the conversation discusses the form of m equations of semi-holonomic constraints, which can commonly be expressed as a sum of coefficients and derivatives of position and time variables. The coefficients aik and ait can be functions of q and q dot. The second equation mentioned is not exactly equivalent to the first, but represents a common special case. The conversation also mentions the use of Latex for displaying equations.
  • #1
maria clara
58
0
m equations of semi-holonomic constraints can be put in the form:

fi=(q1,q2,...,qn,[tex]\dot{q}[/tex]1,...,[tex]\dot{qn}[/tex])

but "commonly appears in the restricted form:

[tex]\Sigma[/tex]aikdqk +aitdt = 0

(i,k,t preceded by "a" should appear in subscript and the sum is over k)

I don't understand this form. what are the coefficients aik and ait? can they be functions of q or q dot?
I don't understand how is it possible for these two equations to be equivalent.
consider for example the following equation of a non-holonomic constraint: q1^2+q2dot=0
what would the second form of this equation look like? :confused:
 
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  • #2
sorry for the last post (couldn't delete it for some reason)... I was confused, but now I realize the second equation is not exactly equivalent to the first, but represents only a special case which is quite common.
 
  • #3
maria clara said:
sorry for the last post (couldn't delete it for some reason)... I was confused, but now I realize the second equation is not exactly equivalent to the first, but represents only a special case which is quite common.

I don't think you can delete the first post in a new thread.

Also, have you taken a look at the Latex tutorial? It's an easy way to display equations.
 
  • #4
now I have, thanks:smile:
 

1. What are semi-holonomic constraints?

Semi-holonomic constraints are restrictions placed on the motion of a mechanical system that can be described by a set of equations involving the coordinates and time derivatives of the coordinates. They are called "semi-holonomic" because they limit the system's motion along some directions, but not others.

2. How are semi-holonomic constraints different from holonomic constraints?

The main difference between semi-holonomic and holonomic constraints is that holonomic constraints restrict the motion of a mechanical system to a specific geometric surface, while semi-holonomic constraints only restrict the motion along certain directions. This means that holonomic constraints are more restrictive and can fully determine the system's motion, while semi-holonomic constraints allow for more freedom.

3. What is the role of semi-holonomic constraints in analytical mechanics?

Semi-holonomic constraints play a crucial role in analytical mechanics as they allow for the application of Lagrange's equations of motion. These equations are essential in determining the dynamics of a mechanical system, and the presence of semi-holonomic constraints can simplify the equations and make them more manageable.

4. Can semi-holonomic constraints be converted into holonomic constraints?

Yes, semi-holonomic constraints can be converted into holonomic constraints by introducing additional variables known as "Lagrange multipliers." These variables can be used to eliminate the non-holonomic terms in the equations of motion, effectively turning the semi-holonomic constraints into holonomic ones.

5. What are some examples of systems with semi-holonomic constraints?

Some common examples of systems with semi-holonomic constraints include rolling objects, such as a ball rolling on a surface, or objects sliding on a frictionless surface. These systems have constraints that restrict their motion along certain directions, but they are not fully determined by these constraints alone.

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