HELP QUICK Non-Uniform Circular Acceleration

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Homework Help Overview

The discussion revolves around the physics of a uniform cylindrical beam falling in a circular path from an upright position. The original poster seeks a formula related to the time it takes for this beam to fall, particularly focusing on the effects of gravity and angular motion.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to derive equations related to the motion of the beam, including torque and angular acceleration. Some participants question the assumptions made regarding the forces acting on the beam and the role of gravity during its fall.

Discussion Status

Participants are actively engaging with the problem, with some providing equations and expressing confusion about the original poster's approach. There is a recognition of the complexity of the problem, and guidance is being offered to clarify the physics involved.

Contextual Notes

The original poster mentions a deadline for a calculus project, indicating a time constraint that may affect the depth of exploration in the discussion. There is also a reference to the exponential increase of gravitational force, which suggests a need for further examination of the underlying physics principles.

mcovalt
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I need a formula by tomorrow morning! Sorry for being annoying, but I am in way over my head.

For a calculus project I said I would do a video on the calculus in a physics problem, but I have no idea how to get the physics formula!

I need a formula to compute the time it takes for a uniform cylindrical beam to fall in a circular path from an upright position with a negligible push (think a pencil falling over after an attempt to balance it on its point).

I know how to compute angular velocity and all those torque questions, but due to the exponential increase of gravity's force while the rod is falling, I have no idea!

Help me out please!
 
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mcovalt said:
I need a formula by tomorrow morning! Sorry for being annoying, but I am in way over my head.

For a calculus project I said I would do a video on the calculus in a physics problem, but I have no idea how to get the physics formula!

I need a formula to compute the time it takes for a uniform cylindrical beam to fall in a circular path from an upright position with a negligible push (think a pencil falling over after an attempt to balance it on its point).

I know how to compute angular velocity and all those torque questions, but due to the exponential increase of gravity's force while the rod is falling, I have no idea!

Help me out please!

Hope you figured it out in time...
 
I thought I did, but I did not. Take a look at my work:

F = -mg
T = -mg (L/2) cos theta
I = (2/3) mL^2

T = I alpha
alpha = T / I = -mg (L/2) cos theta / (2/3) mL^2 = -(3g/L) cos theta

d^2 theta / dt^2 = alpha
d^2 theta / dt^2 = -(3g/L) cos theta

But I am stumped. Because I am taking a late grade on this, help would still be appreciated.
 
[itex]\ \frac{d^2\theta}{dt^2}=\frac{g\sin\theta-\frac{L}{2}\frac{d\theta}{dt}\cos2\theta}{\frac{I_{G}}{mL/2}+\frac{L}{2}\sin2\theta}[/itex]
 

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