studiot

Hello, Will. I hope you read the rules of Quantum Mechanics better than you read the rules of this site. Advertising your site or youtube channel is strictly forbidden. I suggest you post a suitably complete summary before a moderator trips over this post and bans you.

I'm sure it could be very helpful to you to complete this post as I am waiting for you to tell me what you are confused about with Bondi's book. Sorting this out could be much more productive than challenging swansont. Edit I see you have referred several times to 'the river analogy' since you first mentioned the pages in Bondi's book. You did not confirm that I found the correct ones, please do so or refer to the correct ones as the case may be. Please also note that the scanned pages I posted are not an analogy and they are not Einstinian Physics either. They are just plain and simple old Newtonian Physics.

No one is mocking you or your device. The description/specification has changed as this thread has progress. For instance it started off trailing electric cables, but was the promoted to a self contained battery. Initially no mention of recycling the matter ejected from the rocket, this was introduced later in response to a question. For your information , my example, although lurid, was made to conform to the information originally supplied about the workings of the device. Not the claims about thrust and local experts being baffled and so forth. Just this description below. Chucking turkeys out of the window indeed constitutes a matter stream. As you say, ejecting this stream indeed results in a reaction force against the end wall. Again as you say, destroying a % of the streaming birds in flight reduces the mass of the stream and therefore the energy and momentum of the stream which eventually strikes the wall opposite. So the reaction force from the wall opposite (which is rigidly connnected to the start wall) is lower than the reaction force on the start wall. (I tried to make distinguishing easier by using West and East walls.) So it is a perfectly good model to analyse. I have no idea how you actual device works, other than it is different from mine. But I would observe that there are many ways to achieve or prevent motion by redistributing mass within a body, where the necessary reaction is 'hidden'. Often the hidden reaction force is the friction with the supports or ground it stands on. Wheels will spin instead of providing drive in the absence of friction. Nature has a more clever way in the locomotion of a caterpiller, as small children love emulating. Here there is a combination of friction and an increase in distributed normal reaction but moving that reaction from one place to another. I try to teach cyclists to reduce the reactions produced by bumps in the road by simply moving their body weight first backwards whilst teh front wheel goes over and the fowards whilst the back wheel goes over. But the fact remains you have made some factually inaccurate statements about the mechanics of the situation. The most glaring is claiming the operation to be a result of a kinetic energy balance. It is obvious that since you have the ability to supply as much or as little KE from sources external to your 'system' via your electricity supply or via some chemical process, that this is not the reason. Reaction forces come from change of momentum and can be linked numerically to the rate of change of momentum of something. So others here were quite correct to pursue this avenue of enquiry.

Mthematically that is more or less true. I would be grateful if folks would allow me to know just a little bit of basic Mathematics. It is, after all, my subject. Whatever is proposed has to be in accordance with the mathematical rules of 'addition' and 'multiplication'. Both are 'binary operations' that follow specific rules of set and group theory. There is nothing that requires either of the operands to be numbers, or that restricts either from being a number. In Mathematics the unit of the quantity is regarded as a multiplier for the number. Equally we could regard the number as a multiplier for the unit as Capiert has proposed. Regarding either as an operand in an 'addition' between the two does not make sense. However regarding their multiplicative combination as an operand in an addition with another similar (but not necessarily identical) multiplicative combination can make sense in appropriate circumstance. It does not always make sense. I quickly dashed off a couple of examples yesterday to try to help. I am sorry they were so derided as they are correct within the rules of arithmetic I have just described. I can now improve on those examples. Firstly the decimal system itself. Consider the 'number' :- 1234. Children used to be taught that this comprised 1 off of thousands + 2 off of hundreds + 3 off of tens + 4 off of units or 1x(1000) + 2x(100) + 3x(10) + 4x(1) Which is arithmetically correct and conforms to Capiert's original proposition. 1234 could be written in a different way using the Roman (Latin) scheme with different bases.

We recently discussed this video and its rights and wrongs here

So what is 100 + 1 ? It's the same placeholder idea, as is £, s, p

Have you never come a cross aman whose height is 6' 3" ?

It's not an analogy it genuinely shows the characteristics first laid out. Some of those are indeed that momentum analysis is the best way forward. It also shows, IMHO, that the OP omitted the crossways analysis by tring to use a perpendicularity condition. But I'm sure you and exchemist know that.

I couldn't afford the contract with Gimli

Unless, like me, you have 3 feet. You need the 1 to go with the egg since there are 3 feet in a yard. Or is it 2.4 pints ? Trust the Scots

During the discussion (and as a result of it) the original design of this device seems to have changed several times. So here is the Christmas version of my understanding of the original proposed mechanism. Imagine a large Xmas fair hall. On the East wall is an oven ready turkey booth. Unfortunately something has gone wrong with the electrically driven conveyor and packing machine. So instead of being brought up in a steady stream, packed and stacked, the turkeys arrive and are flung out of the window towards the west wall. On the South wall there is a shooting gallery. The elf here thinks the stream of flying turkeys is great fun and has taken to blasting them out of the air to smithereens. However she has to reload between shots and in that time three turkey pass by, impacting the west wall and falling to the ground. So the number of turkeys impacting the West wall is 3/4 the number leaving the East wall. In other times I would tell the story about flying beer bottles and a mad bartender as more fun.

I thought you didn't understand it.

Yes of course he's right. The best way to think about it to to understand the word 'units'. A unit is 1 whole of anything. Even easier to think in terms of something that only comes in whole numbers for example eggs. So the unit is a single egg or 1egg. 5 eggs The 5 and the eggs are separate. So we have 5 x 1_egg. Similarly 5 metres is really 5 x 1_metre

I was working round to the vibration idea as I wondered if this KE reducer was suspended from the case by the diagonal lines in the diagram. And while yes momentum analysis is a good way of analysing the sytem I think the OP's problem is answering the questions The momentum of what ? The energy of what ? The KE is only the KE of the 'rocket' exhaust, not the system. The momentum is only the momentum of the rocket exhaust. But the rocket exhaust by itslef is a different system. It is so common for people to try to change systems in mid analysis and then wonder why things don't add up. It took long enough for the OP to admit that the system needed energy input (the electrical cables) or energy stored in another form eg chemical.

+1 +1

Our Math teacher worked on a weekly cycle. He didn't need, use a textbook except to set homework. I will start the cycle on a Friday. On Friday he picked up the textbook and looked at the set questions for the section/chapter he had been teaching that week. He picked out several questions saying do questions 3,5,6, and 9 or whatever. The other subject teachers knew to avoid weekends for homework. On Monday he would pick up the chalk, stand poised at the blackboard and say OK Smith, question 3 start me off. He would then write on the board whatever Smith said and the rest of the class were expected to comment if they disagreed. Once Smith had a correct start he would switch to Jones for the next step and so on until the answer was written on the board. In this way the whole class worked collectively through all the questions sometimes into Tuesday as well. He said, "I don't mark homework, you mark your own. At this stage you are old enough to realise the only person you can cheat is yourselves." On Tuesday/Wednesday he would walk up and down in front of the board expousing that week's theory and writing it on the board in his own way from memory. We would copy it down (enough time was given unlike at university). We could also stop him and ask for clarification or challenge a mistake at any point. He would always explain the point and not move on until it was clear. Thursday and Friday we would work collectively through example questions he dreamt up on the spot, in much the same way as the homework set on Friday. His comment on the textbook, "Now you are in the senior class you may be pleased to see that the (numerical) answers are in the back of the book. You may think that is great but will find it a introduces its own burden as you will not want to leave a question until you have got that answer."

What is not moving in the horizontal (x) direction in your coordinate system ?

Yes but it's more than just momentum. I think the poster has difficulty deciding what to include in the system, like many folks before him.

The wedge M is moving sideways to the right only. It has zero vertical movement. mass m is moving downwards and to the horizonally to left relative to the floor, but at the same time it is sitting on wedge M so is also moving to the right the same as wedge M. So mass m has a net sideways movement relative to the floor of two motions. Does this help? Hint think about what swansont said about coordinate systems.

+1 We are all working towards showing that with proper analysis the proposed system can be analysed conventionally, as expected once all the details are teased out.

How can I consider curvature flat ? What does this mean? I asked because I am questioning the quote from Quora and your understanding/use of it.

This comment might help you look further.

No problem about the clarity I understood the question well enough and that's what discussion in Homework help is for. Yes you are correct that the wedge M slides along the table or floor in the horizontally opposite direction to the mass m. It is important to understand that this happens while the mass m is sliding down the slope. So the motion of the wedge M is simple, but the motion of mass m is complicated because it's total acceleration is the resultant of three accelerations. Can you see what these are ?

Thank you for this information. +1 Obviously my scribe was having a bad hair day since so many misunderstood his scribblings. I didn't say my link supports or does not support any particular source of water vapour. I said it states that water vapour is the biggest single contributor. It doesn't matter how the water got there it all adds up. So consider the skies over a desert termite. How much water vapour is present ? All this discussion is proving is that atmouspheric dynamics is complicated and multifactorial. In the carboniferous period carbon dioxide levels were high as were temperatures. But then so were oxygen levels. Do you consider oxygen a greenhouse gas ? We couldn't have either water or carbon dioxide without it.

So you are using some of that electrical input to stuff the genie back in the bottle, sorry drive the compressor, also inside the box to repressurise the gas cylinder ? The question was not answered, just neatly side stepped. What else are you not telling us ?