Mechanics: Degrees of freedom (extremely simple)

In summary, the equation of constraint for a particle sliding along a wire rotating at a constant angular velocity w can be expressed as theta' - w = 0 in polar coordinates and wx - y' = 0 in cartesian coordinates. This can be achieved by using a coordinate transformation from polar to cartesian and defining theta in terms of x and y as sin(theta) = y/r and cos(theta) = x/r.
  • #1
tomedj
2
0

Homework Statement


A particle slides along a wire which is rotating at a constant angular velocity w. In polar coordinates the equation of constraint is :

theta' - w = 0 OR theta - wt = 0. *

What is the equation of constraint in cartesian coordinates?


Homework Equations





The Attempt at a Solution


Is it:

wx - y' = 0 * ?

*all primes are derivatives wrt t.

Thanks in advance, I know it's basic but I've hit a wall and have been looking at it for way longer than is healthy...
 
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  • #2
Can't you just do a coordinate transformation from polar to cartesian? How is theta defined in terms of x and y?
 
  • #3
cepheid said:
Can't you just do a coordinate transformation from polar to cartesian? How is theta defined in terms of x and y?

sin(theta) = y/r and cos(theta) = x/r etc.

It's not that simple is it? I could cos or sin both sides of theta = wt but the I'll get something that looks like:

y/r = sin(wt)...
 

What is the concept of degrees of freedom in mechanics?

Degrees of freedom refers to the number of independent variables or parameters that can affect the motion of a system. In mechanics, it is used to describe the number of ways a system can move or the number of independent coordinates required to fully specify the position of a system.

How are degrees of freedom related to the complexity of a system?

In general, the more degrees of freedom a system has, the more complex it is. This is because a higher number of degrees of freedom means there are more variables or parameters that can affect the behavior of the system, making it more difficult to predict or analyze.

What is the difference between constrained and unconstrained degrees of freedom?

Constrained degrees of freedom are those that are limited by external factors or forces, such as a constraint in the form of a fixed point or a restriction on motion. Unconstrained degrees of freedom, on the other hand, are free to move without any external limitations.

How do degrees of freedom affect the stability of a system?

The number of degrees of freedom can have a significant impact on the stability of a system. In general, a higher number of degrees of freedom makes a system less stable, as there are more variables that can lead to unpredictable or chaotic behavior.

Can degrees of freedom change in a system?

Yes, the number of degrees of freedom in a system can change. This can happen due to external factors or forces, such as constraints being added or removed, or due to changes in the system itself, such as the addition or removal of components.

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