Electromagnetic Propulsion

[starfhury]

Sorry to keep extenting this thread, but I'd like to point something out. I don't think it will make a difference, but it might be worth considering. Let's take that famous example of the ice skater on an ice rink. Suppose the skater has ten baseballs. As the skater throws the balls he accelerate in the opposite direction accelerating in that direction. This is how normal rockets work. Now let's take the other example. I stand at the edge of the ice rink with the the ten balls and through them at the skater. As the skater catches the balls he accelerates in the direection the ball was traveling. Now assume the skater release the first ball in order to catch the second ball. In earths gravity field, it would accelerate to the ground. In space it would match the speed of the skater. When the skater catches the next ball he would accelerate leaving the first ball behind.<br /><br />Next and this is what I think Vidar, might be saying and this is also where the conserversation of moment issues comes up. Imagine you have a giant piston inside of a magnetic bottle with in the ship. We use the magnetic energy to impart kinetic energy to the piston. { <--- /> ] sort of like that. Now if we accelerate the piston using the magnetic field in this ---> direction then allow it to impact here ] it will transfer it's kinetic energy to the overall ship. The ship is displaced ---> and the piston goes this way <--- because the ship is displaced. The piston is allowed to drift backwards so to speak. Before it reaches the end of it's travel, the magnetic field are used again to accelerate the piston ---> this way to repeat the process. I think that's what Vidar is trying to say. The problem the we have to answer for him is what the magnetic fields will do. If you used them to accelerate the piston, does it pushes the entire ship in the other direction for no net gain? If that's the cause then Vidar's theory so debunked.<br />As a consideration, let's <div class="Discussion_UserSignature"> </div>

 

[no_way]

<blockquote><font class="small">In reply to:</font><hr /><p> If you used them to accelerate the piston, does it pushes the entire ship in the other direction for no net gain?<p><hr /></p></p></blockquote><br /><br /><b>EXACTLY</b> and this has been explained over and over in like ten different forms here already. <br />It doesnt matter which configuration you use, whether your "impact" throws something away from the ship as in my mass driver example and tries to reel it back in, or whether you impact something against the ship.<br /><br />Just ignore the magnetics entirely, you can do the "piston" thing with a cable or rope as well, and now imagine when you try to accelerate this piston, this means you <b>pull</b> the rope, and rope is pulled from <b>both ends of course</b> thus putting both the ship and the piston in motion.<br /><br />aaargh

 

[vidar]

This is a flat earther<br />http://www.thomasdolby.com/lecture/video.html<br /><br />I am not.

 

[nacnud]

<font color="yellow">If you used them to accelerate the piston, does it pushes the entire ship in the other direction for no net gain?<br /><br /><font color="white">Yes, there is no net gain.</font></font>

 

[larper]

Right. Understanding all of the forces at play in a system is always key. The absolute best example I ever had was from my hight school physics teacher.<br /><br />A virgin princess stands at the window of her tower room. Her father is intent that her suitors do not gain access. Just outside of her window is a wooden pole extending horizontally, like a flag pole on an office building. At the end of the pole is a pully.<br /><br />Just below the window is a metal hook firmly planted into the stonework of the tower.<br /><br />A rope has been threaded through the pully, extending all of the away to the ground at both ends. One end is tied to a large bucket.<br /><br />Along comes the dumb suitor. He jumps into the bucket and proceeds to pull himself up by pulling down on the free end of the rope. The wooden pole seems to be able to hold his weight. <br /><br />He makes it all of the way up to the window no problem. Noticing the conveniently placed hook, he ties off the free end of the rope to the hook. The wooden pole snaps off, and the suitor plunges to his death. The father is pleased that his plan to keep his daughter's virtue intact worked perfectly.<br /><br />Question: Why did the pole break? Would the same thing have happened if the suitor had tied the rope off to the bucket? <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[starfhury]

So there you have it Vidar. I think I did my best to explain your idea, but in the end, in that system no net momentum can be gained in one direction or the other. You'd have an overall net loss of energy, but no gain in momentum since the magnetic fields used to overcome the rearward moving piston exerts it's force against the rest of the ship negating any gains. <div class="Discussion_UserSignature"> </div>

 

[vidar]

Why didn't the King get any grandchildren?

 

[larper]

Nope. that is not the answer. Assume that the pole is short enough and the hook large enough that the rope can be tied of perfectly verically. <br /><br />edit: Although you are right about why it would break in another system. Assume this system is simple. All forces are vertical. No trig required. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[nacnud]

Though so, but then the king would hope that the suitor was just the right weight <img src="/images/icons/smile.gif" />

 

[larper]

Not just the right weight, just not excessively large. The king did have to assume that suiters would have a minimum weight, say 150 pounds, and would not exceed say, 300 pounds. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[somispin]

So we have two problems with vidar's theory (just trying to make everything more comprehensive and concise).<br /><br />1) There is no net external force for acceleration to occur: ie no static friction. - this goes against newtonian science <br /><br />2) Using electromagnetic fields to accelerate the magnet towards the ship may infact pull the ship towards the probe, albeit at a much slower rate, therefore meaning a 0 net gain of speed.<br /><br />3) The electromagnetic fields being used to slow down the probe would also translate into a loss in momentum.<br /><br />Any other problems with his theory...?

 

[nacnud]

I suppose the amour would have to be allowed for...

 

[larper]

Oooh.. bad one. <br /><br />Anyway, should give credit to tigerbiten since he is technically right. The simple answer is that the "weight" on the pole immediately doubled, and was not built to hold that much. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[somispin]

Post deleted by somispin

 

[larper]

No, it is simply that the vectors add to double the forces on the pole. I guess there is a point on the rope (at the point of contact with the pulley) that experiences 2x tension.<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. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[somispin]

Why does the weight on the pole immediately double when he ties the rope to the hook?<br /><br />And how, if hte rope is equally long on both sides of the pole, did he manage to tie the free end of the rope to the hook?

 

[larper]

<blockquote><font class="small">In reply to:</font><hr /><p>Why does the weight on the pole immediately double when he ties the rope to the hook? <p><hr /></p></p></blockquote><br />That is exactly what you have to figure out.<br /><br />The free end of the rope does not need to be used. Ok, the suitor drops a few feet, catches the sill of the window, and shags the princess. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[somispin]

I get it!<br /><br />Just one question that wasn't answered, that sort of adds an incongruity with the idea. You said that the rope was equally long on both sides of the pulley. The man was on the side of the rope with the bucket, and he pulled the other side of the rope to move himself upwards. So how did he have a free end of the rope to tie onto the hook?

 

[larper]

Sukath! His eyes open! <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[larper]

Who needs a free end to tie off a rope? <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[somispin]

Isn;t it impossible to tie off a rope if you dont have the free end?

 

[larper]

You know, I have to giggle about some of the questions impuning the logic of the situation. Very much like a real HS physics classroom. You have some people who understand the question being asked, then you have the "english majors"....<br /><br />"Was he wearing armor?"<br />"How did he get the free end of the rope?"<br />"Why didn't the king like the suitors?"<br />"Did the suitor have a big lunch before hand?"<br />"How did the suitor fit in the basket?"<br />"What was the basket made of?"<br />"Did the princess like the suitor? Maybe she put extra weight in the bucket so he would fall."<br />"Why didn't the suitor use the door?"<br />"Why would the king rig such a contrived way of getting rid of the suitors?" <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[somispin]

<br />still havent answered my question about the free end of the rope. looking forward to the answer. i get the problem though.

 

[larper]

Assume A in this case is 0. Then the total load is<br /><br />x ((sin A)^2 + (1+cos A)^2)^0.5 <br />x(0 + (1+1)^2)^0.5<br />x(2^2)^0.5<br />2x <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

 

[larper]

I can tie off a rope without a free end. Do it all of the time. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>