The acceleration of a moving pendulum

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    Acceleration Pendulum
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Discussion Overview

The discussion revolves around the acceleration of a pendulum bob in a non-ideal scenario where friction is present. Participants explore the nature of the pendulum's acceleration throughout its motion, questioning whether it remains constant or varies based on the pendulum's position and forces acting on it.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant claims that the acceleration of the pendulum bob is constant throughout its journey.
  • Another participant questions the assertion of constant acceleration, seeking clarification on what is meant by it.
  • A different viewpoint suggests that the initial acceleration of the pendulum depends on its angle from the vertical, with varying acceleration as it moves through its arc.
  • Some participants argue that if the acceleration were constant and zero, the pendulum would not move at all, indicating a misunderstanding of the dynamics involved.
  • It is proposed that the total acceleration is not constant due to the changing direction of the force exerted by the pivot point, which adds complexity to the pendulum's motion.

Areas of Agreement / Disagreement

Participants express differing views on whether the acceleration of the pendulum bob is constant or variable, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

There are assumptions regarding the definitions of acceleration and the effects of forces acting on the pendulum that are not fully explored. The discussion also highlights the complexity of the pendulum's motion in the presence of friction and varying forces.

Kyoma
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A pendulum bob is released from a height in a non-ideal situation (that's there is friction). What I don't get it is the fact that the acceleration of the pendulum is actually constant. Why?
 
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I'm not quite up to speed on pendulums, what do you mean by the acceleration is constant?
 
The acceleration of the bob is the same throughout its journey. So, if a = 0, then it will be zero throughout its journey.
 
My understanding is that a pendulum dropped from point X has an intial acceleration due to gravity that depends on the angle of the pendulum from its pivot point. The closer to horizontal it is, the greater the inital acceleration. Once it passes that, the accelerations lessens and at the vertical point the acceleration is zero. After passing veritcal, the deceleration increases up to horizontal and then decreases after that. If the pendulum was dropped initially from below horizontal, the deceleration simply decreases until the pendulum reverses direction and then increases again.

That is my understanding of it. Is there something I've missed here?

The acceleration of the bob is the same throughout its journey. So, if a = 0, then it will be zero throughout its journey.

I don't see how the acceleration could be zero. If it was the pendulum wouldn't move at all.
Are you talking about the increase or decrease in acceleration?
 
If the acceleration is the same, it won't go back and forth, so it's not much of a pendulum.
 
The total acceleration is not constant. The acceleration due to gravity is constant, but the acceleration due to the force exerted by the pendulum's pivot point keeps changing direction. The total acceleration is the sum of gravity and that from the pivot point and it keeps changing. If pivot was cut so that it could no longer provide a force, the pendulum would just keep falling.
 

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