Calculate Angular Momentum of Falling Ball

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    Falling Pole
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Homework Help Overview

The problem involves calculating the angular momentum of a ball that is initially fastened to a flagpole and then falls when it becomes loose. The scenario includes a flagpole connected to a building, with specific angles and distances involved in the setup.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the formula for angular momentum and question the appropriate trigonometric function to use based on the angles provided. There is also a debate about the interpretation of the ball's motion after it becomes unfastened, with differing views on whether it falls straight down or swings.

Discussion Status

The discussion is ongoing, with various interpretations of the problem being explored. Some participants have provided insights into the angular momentum calculation, while others are seeking clarification on the setup and motion of the ball.

Contextual Notes

There seems to be ambiguity regarding the motion of the ball after it becomes loose, as well as the specific angles involved in the calculations. This may affect the approach to determining angular momentum.

UrbanXrisis
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A ball of mass m is fastened at the end of a flagpole connected to the side of a tall building at point P. The length of the flagpole is l and [tex]\theta[/tex] is the angle the flagpole makes with the horizontal. The ball becomes loose and starts to fall. What is the angular momentum of the ball about point P?

so angular momentum is L=mrvsin(theta)

in this problem, the angle between force downwards and the radius is not given, but the angle beween the building and the radius is given. Therefore, sine cannot be used. Cosine must be used for this specific problem.

v=at
v=-gt

[tex]L=-mlgtCos\theta[/tex]

is this the correct way to approach this question?
 
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I believe your description of this problem is lacking. I picture a ball that's fastened, and when it becomes unfastened it just falls straight down...
 
That's the way I interpreted the question as well. Do you perhaps mean that the flag pole becomes loose and swings down to hit the building? Perhaps then you may be looking for the angular momentum of the ball on the end of the pole...
 
I interpreted the problem similarly. Assuming the problem is "What is the angular momentum of the falling ball (with respect to a point on the wall) as a function of time?", then UrbanXrisis's answer is correct. (Maybe he can restate the problem.)
 

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