How Fast Does the Center of Mass of a Falling Stick Move?

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The discussion revolves around calculating the speed of the center of mass of a falling stick using both force and energy methods. Participants analyze the forces acting on the stick and derive equations for acceleration and torque. They explore the relationship between angular motion and translational motion, emphasizing the importance of considering the stick's horizontal movement due to the lack of friction. The conversation includes attempts to solve differential equations and verify the correctness of derived expressions for angular velocity and center of mass velocity. Ultimately, they arrive at a formula for the center of mass velocity, highlighting the complexity of the problem and the collaborative effort to reach a solution.
  • #31
Tanya Sharma said:
So, $$ ω^2 = \frac{12g(1-cosθ)}{L(3sin^2θ+1)} $$ looks alright to you ?

I like it :smile:

Tanya Sharma said:
And then

$$ v_{cm} = -\frac{L}{2}(\dotθsinθ) $$

gives $$ ω = -[\frac{3gL(1-cosθ)(sinθ)}{(3sin^2θ+1)}]^\frac{1}{2} $$

Is this fine ?
why minus? And you miss a factor of 2. $$ ω =2\sqrt{ \frac{3g(1-cosθ)}{L(3sin^2θ+1)} }$$

and Vcm=-ωsinθ L/2.
 
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  • #32
Oh ! that was a typo..I meant

$$ v_{cm} = -[\frac{3gL(1-cosθ)(sinθ)}{(3sin^2θ+1)}]^\frac{1}{2} $$

Minus makes perfect sense...
 
  • #33
Tanya Sharma said:
Oh ! that was a typo..I meant

$$ v_{cm} = -[\frac{3gL(1-cosθ)(sinθ)}{(3sin^2θ+1)}]^\frac{1}{2} $$

Minus makes perfect sense...

$$ v_{cm} = -[\frac{3gL(1-cosθ)(sin^2θ)}{(3sin^2θ+1)}]^\frac{1}{2} $$
sinθ has to be squared if you pull it under the square root. But otherwise it is perfect:thumbs: Have a good rest, you deserve it. :smile:

ehild
 
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  • #34
ehild...I am falling short of words to express my gratitude...All I will say is "THANK YOU ehild" .

You rock! :smile:
 
  • #35
Tanya Sharma said:
ehild...I am falling short of words to express my gratitude...All I will say is "THANK YOU ehild" .

You rock! :smile:

You are welcome. That was a challenging problem. I am also exhausted :smile:

ehild
 

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