Electromagnetic Propulsion

[somispin]

I get the problem without the math. Anyone wanna take the time to explain the math?> I think im doing it this year? Please? <br /><br />eg: what is sin. what is cos. how does that equation fit into the context of the problem.

 

[somispin]

Took me a long time of playing around with it, but i think i get it now. thanks alot.

 

[somispin]

Hmm.<br /><br />But larper said:<br /><br />"Remember, this is a simple hs physics statics question. No trig required, no materials knowledge needed, etc. It is all simply about adding up all of the forces on the pulley."<br /><br />So how is it possible, under what he said, that if you tie the rope to the bucket, the pole wont snap (it is still an added force) and if you tie the rope to the hook, it will snap?

 

[vidar]

Starfhury<br /><br />The generator keeps on providing energy. The hammer keeps on beating and transforms electric energy to kinetic energy. That constant flow and transformation of energy do not stop. It seems to be the common opinion that all of the kinetic energy transforms to any kind of energy, except (staying) kinetic.<br /><br />That I find very unlikely and still contradicts it.<br />

 

[nacnud]

Post deleted by nacnud

 

[nacnud]

All the energy is converted to heat which slowly ebs away into space. <br /><br />After all heat is just vibrations at a molecular/atomic level and by now you should have realised that your drive would just sit there - throbing.

 

[drwayne]

"The hammer keeps on beating and transforms electric energy to kinetic energy."<br /><br />Only if it generates motion. This problem does not solve itself by simply stating that some of the energy goes into kinetic energy, hence motion.<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[tap_sa]

While I know that patting your own back doesn't create motion here's a possibly stupid question that this thread brought into my mind; Is it possible to create thrust without expelling reaction mass? IOW some sort of mechanical device, a box, energy goes in and the box wants to move to some direction (without interacting anyway with outside world except maybe radiating some of that energy as heat). The catch is that it can't move to the direction of the thurst even an ångstrom or the thrust dies out.<br /><br />Something like this would be handy in making the long expected aircar. Propellers would lift it and move forward but thrust-box would help cancel the gravity. I'm fairly certain that there's some law that makes it impossible but can't spot it right away.<br /><br />

 

[larper]

You have to ask yourself, "How much weight at any time is the pole supporting"?<br /><br />Using ASCII graphics sucks, but imagine looking "down the barrel" of the pole.<br /><br /><pre><br /> O<br /> | |<br /> | |<br /> | |<br /> .| |<br /> B</pre><br /><br />Now, gravity pulls on B(ucket). Given no friction in the pulley, the hook (.) must supply all of the force to resist gravity. So, at any point along the rope, the downward force is the same. Pick two points, x and y....<br /><br /><pre><br /> O<br /> | |<br /> | |<br /> x y<br /> .| |<br /> B</pre><br /><br />There are equal downward forces on x and y, and that force is equal to the weigth of B. Thus, at point O, the downward force is doubled. Thus, at point 0, a force of 2*W must be applied to keep the system in equilibrium.<br /><br />This is a simple way of exlaining it, but it is true. Try it with a spring scale....<br /><br />Tie a string to a mass. Weigh the string and mass using a spring scale. You get weight W. <br /><br />Now, tie the free end of the string to your shoe. Now, pick up the mass using the string. The spring scale will register 2*W weight.<br /><br />Here is yet another way to think about it. Using a single pulley, you are to lift a mass off of the ground. How much "pull" do you have to apply to the rope to lift the mass? The answer is the weight (W) of the mass. So, there you are, holding a rope applying W force to the rope to hold the mass in the air. Gravity is still pulling on the mass too, so it is pulling on the rope with force W. At the point of the pulley, two W's are being applied in a downward direction.<br /><br />This is exactly the principle of a pulley. It multiplies forces. A single fixed pulley used to pull something up does not really make it evident, but invert the system. You are to raise a weight from the ground and you stand ABOVE i <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[nacnud]

<font color="yellow">I'm fairly certain that there's some law that makes it impossible but can't spot it right away. <br /><br /><font color="white">Conservation of momentum.</font></font>

 

[tap_sa]

It's impossible to create even steady, non-moving thrust (ie it doesn't do any work) without 'unconserving' momentum?

 

[larper]

<blockquote><font class="small">In reply to:</font><hr /><p>In tieing the bucket to the side you add additional side force on the beam.<p><hr /></p></p></blockquote><br />It does not matter where you tie it off. For simplicity's sake, imagine tying it off below the pulley. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[mrmorris]

<font color="yellow">"No, it is simply that the vectors add to double the forces on the pole."</font><br /><br />I can't see the vectors whereof you speak. It appears that absent any possible sideways vectors spoken of earlier... the forces remain constant. I've attached (assuming I remember to) a picture of the vectors involved. If Prince Albert in a Bucket weighs 150 pounds, then the downward vector on the rod is going to be 150 pounds... period. It matters not whether Al is holding one end of the rope or is is tied to something (be that the bucket, a convenient hook, or Princess Virginia's brassiere).<br /><br />Please show what vectors you think will double the weight. BTW -- correct or not, this is a <b>much</b> more interesting topic than sledgehammer spacecraft propulsion.

 

[drwayne]

I am confused by the wording if your question. (Maybe it has to do with finishing these charts for tommorrow) Care to take another shot at conveying your idea/question?<br /><br />Wayne <div class="Discussion_UserSignature"> <p>"1) Give no quarter; 2) Take no prisoners; 3) Sink everything."  Admiral Jackie Fisher</p> </div>

 

[nacnud]

It the force isn't doing any work then its not going to help fly your air car.

 

[john_316]

Ok here is one for you mathmatic and physics majors...<br /><br />Using time and warp given in 4 to 6 dimensions of space theories give me a mass (rocket) of 300 tons and make it move at 3 times the speed of light?<br /><br />And yes now E=mc2 can be played with...<br /><br /><img src="/images/icons/smile.gif" /><br />

 

[mrmorris]

<font color="yellow">"Finally, one more view is the view of the suitor: How much force did he have to apply to rope while he was pulling himself up? Exactly half of his weight! He did not have to be able to do a chin up, he only had to be able to pull half his weight, not his whole weight. "</font><br /><br />Wrong. You're thinking that this example is getting a mechanical advantage from the pulley... but this is not true given the situation described. The mechanical advantage from a pulley system can be determined by dividing the number of 'effort' lines into the number of 'load' lines. In this case, there is one load line and one effort line. The ratio is 1-1 and the prince must pull his own weight. A document on pulleys and mechanical advantage can be found here.

 

[tap_sa]

There a 'black box'. You put energy into it, either there's a rotating axel going in or electricy. Is it now possible for someone to feel a constant push by that box, ie the box would like to move to some constant direction. But if you'd let it free the force would instantly die out without the box moving ... hmm... IOW the box would exert counter force only if something tried to push it. For example when gravity tries to pull the box down it would resist it.<br /><br />Maybe this is just a more peculiar form of self-back-patting <img src="/images/icons/smile.gif" />

 

[tap_sa]

<font color="yellow">"It the force isn't doing any work then its not going to help fly your air car."</font><br /><br />If it could just counter the gravity that would help to make more silent car because no need for huge helicopter-like propeller.

 

[larper]

No, I am right. As the suitor applies a force to the rope, he is "reducing his weight". At equilibrium, the weight on each rope is exactly half of his weight. So, he has to apply only a little more to actually move himself up. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[mrmorris]

<font color="yellow">"As the suitor applies a force to the rope, he is "reducing his weight". "</font><br /><br />Ayup -- you're actually correct. The 'reducing his weight' isn't really a valid statement -- he's splitting his weight between the two ropes. However -- I see what is being demonstrated. By keeping all of the forces internal to the system, the downward vector sum on the pulley/pole is 150 pounds. Once an external force is supplied (i.e. the hook), then the vectors double. The force difference is not 'mechanical advantage' as is generally associated with pulleys. I updated the picture for chuckles...

 

[tap_sa]

Bah, stupid me. If the box won't react with any external field like magnetic or so, the only way it can create force is via the age old F = m*a, meaning there must be mass accelerating some constant way. Oh well, kinda guessed it must be something simple because of the lack of silent aircars <img src="/images/icons/smile.gif" />

 

[somispin]

I have another question. When attempting to solve this problem triganomitrically, (sp?) how does one determine what sin and cosin are? And why do the angles need to go after sin and cosin?

 

[nacnud]

Given a right angle triangle where the longest side is one, <br /><br />cos &#952; = length of the side adjacent to &#952;<br /><br />sin &#952; = length of the side oposite to &#952;<br /><br />clear as mud? <img src="/images/icons/smile.gif" />

 

[nacnud]

Drat, &#952 = theta (O with a line through it)