- #1
amjad-sh
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Homework Statement
A stick of length L and mass m lies on a frictionless table.A force parallel to the table top,[itex] \vec{F} [/itex],is applied to one end of the stick for a very short time [itex]\int F \, dt[/itex][itex]=[/itex][itex]\vec{I}[/itex],the"impulse".Choose a convenient set of two generalized coordinates.Interms of your choices of generalized coordinates,what are the generalized forces when [itex]\vec{F}[/itex][itex]\neq[/itex] 0?What is the subsequent motion of the stick?
Homework Equations
[itex]\frac{d(\frac{\partial L}{\partial\dot{x}})}{dt}-\frac{\partial L}{\partial x}=0 [/itex]
where L is the Lagrangian of the system L=T-V.
[itex]\sum_{i=0}^M \vec F_{i}\cdot \frac{\partial \vec r_{i}}{\partial q_{k}}=f_{k}[/itex]
where [itex]f_{k}[/itex] is the generalized force and [itex]\vec F_{i}[/itex] are the non-constraint forcesand[itex]q_{k}[/itex] is the generalized coordinate.
The Attempt at a Solution
Actually I couldn't obtain 2 degrees of freedom.I think they must be 3,which are θ,Φand z.
But I supposed that θ is fixed.So the degrees of freedom are now "z" and "Φ".
z isthe distance between the origin O and the lower end of the stick. Φ is the angle between the stick and z as shown in the figure below.
[itex]d\vec r_{i}=(z-dl\ cos\phi)\vec e_{r}+{dl}\ sin\phi\vec e_{\theta}[/itex]
and [itex]\vec {r}=(z-l\cos\phi)\vec e_{r}+l\sin\phi\vec e_{\theta}[/itex]
I reached here, and then I didn't know how to proceed.
Any hints?