Need Help Explaining a Physics Video? Let Us Help! | Expert Tips

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Discussion Overview

The discussion revolves around a physics video demonstrating a contraption involving magnets and motion. Participants explore the mechanics behind the device, its feasibility, and the principles of energy conservation. The conversation includes technical reasoning and speculative questions about the forces at play.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant expresses skepticism about the contraption's functionality, suggesting it may be misleading and questioning the energy dynamics involved.
  • Another points out that the final machine spins in the opposite direction compared to the initial demonstration, indicating a potential flaw in the design.
  • A participant notes the behavior of magnets in the video, observing that they start close together and then separate, and questions whether all devices were constructed by the same individual.
  • One contributor discusses energy conservation principles, suggesting that energy in a closed system remains constant and that friction plays a role in energy transfer.
  • A participant raises a question about the effect of stronger magnets on the forces involved in the contraption, indicating excitement about the inquiry.
  • Another participant speculates on the mechanics of the device, proposing a "flywheel effect" and discussing the initial potential energy involved in the system.
  • There is a mention that the machine did not speed up after its first turn, raising further questions about its operation.
  • One participant clarifies the relationship between the strength of magnets and gravitational forces, emphasizing that stronger magnets exert greater forces, while gravity's effect depends on mass.
  • Another contributor reiterates the energy dynamics, explaining that energy input and output in the system are balanced and cannot exceed the energy put in.

Areas of Agreement / Disagreement

Participants express a range of views, with some agreeing on the principles of energy conservation while others contest the functionality of the device. The discussion remains unresolved regarding the effectiveness and mechanics of the contraption.

Contextual Notes

Participants reference various assumptions about energy transfer, the role of friction, and the behavior of magnets, but these assumptions are not universally accepted or clarified. The discussion includes speculative elements that are not fully substantiated.

projectearth
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I've only taken one physics class. I'm not too knowledgeable yet in science, but I was hoping someone can help me explain this video to my brother.

http://www.youtube.com/watch?v=zqG-TL0WnjE&feature=BFa&list=HL1343828606

I'm assuming he has a battery in one of the wooden blocks that holds the final contraption up. Although it looks very convincing, my brother wants me to build one. Maybe someone could give me a good reason not to waste my time hah.

Thank you guys.
 
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The final machine spins the opposite direction as the example devices move. If the device would move as s/he demonstrated in the beginning, it would be spinning the opposite direction. DEBUNKED! And no need to even talk about energy!
 
Actually if you look at the green skateboard wheel the magnets start close together then separate as it moves away. The same is for the final guy. Also important to mention, I don't think this were all built by the same person.
 
You're right. It's just the middle of the three that moves in the opposite direction. Either way, the energy conservation always works.
I wouldn't think of it as a waste of time if you have fun and explain to your brother why it won't work. In case you don't know, the reason it won't work is that energy in a closed system (there is no flow of energy in or out) will stay the same. Since there must be friction transporting energy from the system into the environment, there must be energy being transported in.
But building might still be fun.
 
Thanks you DrewD I agree. I guess ill just try. A question I do have, if you don't mind.. If gravity pulls down a magnet which exerts a force against the other magnets causing it to rotate. Will this force change if the magnet is stronger? I'm assuming so, i guess I am excited now..
 
I have to confess that last one weirded me out. I can't say for sure how it works. My tentative guess, though, is that it's a flywheel effect. You notice how it's pre-loaded. The initial locked position has the cam raising the upper bar against gravity, so you're starting off with PE. I'm surprised at how long it ran without seeming to slow, but he did force it to a stop at the end. If he hadn't, we might see it stop on its own in another minute or so. I'd say we're looking at a kind of flywheel that gets its initial push from what amounts to a pre-loaded spring.
 
I notice that the machine didn't speed up after it's 1st turn...
 
projectearth said:
If gravity pulls down a magnet which exerts a force against the other magnets causing it to rotate. Will this force change if the magnet is stronger?

I'm not quite following what you mean. A stronger magnet, with all else kept the same, will exert a greater force compared with a weaker magnet. I don't understand why that excites you.
 
projectearth said:
Thanks you DrewD I agree. I guess ill just try. A question I do have, if you don't mind.. If gravity pulls down a magnet which exerts a force against the other magnets causing it to rotate. Will this force change if the magnet is stronger? I'm assuming so, i guess I am excited now..

There are two forces to think about. The first is the force between 2 magnets. This gets stronger with stronger magnets. The 2nd is the force of gravity. This only gets stronger if your magnet has more mass. The key to both of these forces is that they are effectively "one way" energy generators. What I mean is that it takes just as much energy to lift something up against gravity as you got by having it fall, and you have to expend as much energy to push or pull magnets apart as you generated by letting them come together or move apart in the first place. It is not possible to generate more energy than you input into the system.
 

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