Kinematics Problem Solving - Physics Solutions

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Discussion Overview

The discussion revolves around a kinematics problem involving a pendulum and its motion in relation to a slider. Participants explore the conditions for maximum angle (##\theta_\text{max}##) and the relationship between acceleration and angle in a dynamic context.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • Some participants suggest that the condition for maximum angle occurs when the pendulum and slider have the same acceleration, which they propose is ##a = g##.
  • One participant questions the occurrence of ##a = g##, suggesting it would only happen if the wire breaks.
  • Another participant identifies the equilibrium angle as ##\pi/4## and discusses the motion around this angle, indicating that the initial condition is ##\theta = 0##.
  • There is a mention of two solutions for the maximum angle condition, although the specifics of these solutions are not detailed.
  • One participant expresses a need for equations to clarify the motion, indicating that informal reasoning is insufficient.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specifics of the motion or the conditions for maximum angle, with multiple competing views and some uncertainty remaining regarding the correct approach.

Contextual Notes

Participants reference a specific problem (problem 3/92) and mention the use of polar coordinates, but the discussion lacks detailed mathematical formulations or clear definitions of terms used.

ramadhankd
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Homework Statement
The homework statement/question is in my post.
Relevant Equations
So does the equations and attempted solutions. I just wanna ask whether or not my solution is correct, because the question has a triangle symbol on It, and It supposed to be complex. Solving It that easily gives me anxiety. Please kindly help.
Thanks.
1570165273565.png
 
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Seems to me you describe some equilibrium situation. What would ##\theta(t)## look like ?

[edit] And I don't see when ##a=g## would normally ever happen (unless the wire breaks :biggrin: ).
 
It's actually a dynamic question. The question is on the top left in my post (problem 3/92). We need to find the value of maximum theta. In my opinion, this condition will be reached when the pendulum have no relative motion with the slider, thus having the same acceleration a = g. I just wonder if this condition I set for max theta is right. Also, I use polar coordinate approach to analyze the kinematics while in the end, It doesn't matter at all because I only need to project a into r and theta component of acceleration (the value of r, and other defining properties of a polar system doesn't matter). Is this right?
 
I should have read the small print ...

So the equilibrium ##\theta## is ##\pi/4## and the pendulum swings around that angle. Any way to describe the motion ? With the initial condition ##\theta = 0## the answer seems easy.

I think your condition for ##\theta_\text{max}## is correct - but it leads to two solutions.
 
For the motion description, I think that the motion is that the pendulum has the constant acceleration a when θ=θmax. As for the two solutions, what are those? I'm sorry for the late reply, I've been out this weekend.
 
You don't list any equations to determine the motion. 'I think' doesn't help.
 

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