studiot

Well I have been thinking about a suitable description for you. This would entail quite a bit of work for me. BUT With that response to my last post I don't believe you would actually read it, any more than you appear to have read Eise's good efforts on your behalf. I see he hasn't bothered again. If I posted some mathematics would you be able to understand it? In theory you are the one challenging established mathematical physics so you should be the one posting supporting mathematics. We can only help you if we all work together.

No I don't agree with you there. But then I only partly agree with the other contributors to this discussion. Knowledge, understanding, skill, reaoning, imagination, visualisation (and other cerebral activities) are all different. That is why we have so many different terms or words in English. That is not to say that there is no overlap. Yes there is overlap but there is also disjunction between the terms. That is why activities often entail combinations of those qualities. Like a Venn diagram with union or intersection. Just to note about knowledge without understanding two examples: Many drive a car without the faintest understanding of how it works. Most elementary calculus courses develop a good deal of manipulative skill and knowledge, but I don't think many of the pupils have much understanding of calculus.

Only one of your posts is more than one line long. Why would anyone put more effort into answering than this? Are you having trouble with the English language? What level should we be pitching answers at mathematical or just explanatory?

No I told you that in post#7. Try asking questions directly related to what others have told you and you will get much more out of the conversation.

I'm sorry to tell you that you are being tracked all the time, and it has nothing to do with your IP address. Perversely, the older your computer the harder it is for the modern tracking to work, Windows 10 is by far the worst of all. Accessing your files is a different matter, you have more conrol here.

A good length description setting out your stall. Well done, most seem to make their OP too long or too short. However I fear you have misunderstood frames of reference. Why do you say that the apple and the satellite are in different frames of reference? You haven't explicityl mentioned the centre of the Earth, but by your reasoning this should be in yet another frame. Further you state that the 'distance between them is not changing. How are you reckoning this distance? In which frame of reference? Please explain.

I would add a note to the effect that other compounds containing chlorine in solution in water may well release chlorine gas, with or without heating. This can often be detected by smell in certain tapwaters and showers

Surely this belongs in the crackpot section, not alongside 'other sciences' like hairdressing or dog grooming.

Thank you , that is younger than I guessed. But I am more interested in what science you know and what you thought about my explanation. So that I can connect it to what you already know.

Hello Sigmarus, I see your main interest is Chemistry and that you are in 'lower-secondary' so I will try to pace the answers accordingly. To offer best help I will split my answer into two parts (posts) and also ask a couple of questions about your actual study level. I am guessing that you have completed one year of what we call the sixth form in the UK which means you will have studied 'force statics' and understand what equilibrium means but not yet studied dynamics or kinematics. As a chemist you will also have heard of the law of conservation of energy. Please confirm or correct these guesses. So first to answer your question as to why friction opposes motion. This is entirely due to the law of conservation of energy. Imagine a rough block sitting quietly on a rough surface ( We say a rough surface when friction is involved and a smooth surface etc when friction is not involved) Now let us start to pull it along and then let go of the pull. If the friction acted in the direction of motion and we removed the pull, the block would continue to move under the action of the friction alone. We know that does not happen and I hope you can see that if it did it would contravene the law of conservation of energy. What we observe is that the block slows to a standstill as the kinetic energy is dissipated as work against the frictional force. If you like this we can study your other question (about the spring balance) in more detail. These are good questions, by the way, so keep asking them. +1

First class summary list, StringJunky, inlcuding some things I had not heard of. Thank you +1

Yes and no. Schrodingers wave equation is a differential equation of motion and applied pretty generally. As such it has many solutions, most of which are useless to us. We need to select the apppropriate one by applying the appropriate boundary conditions. This is where the pictures Eise showed you come in.. They are for what is called a 'particle in a box' or a potential well which means that a negatively charged particle (electron) is subject to a potential well near the positively charged nucleus due to electrostatic interaction. The solution must have 'nodes' at the box edges (points of zero amplitude) like a standing wave on a string in classical mechanics. It is this requirement that introduces the quantisation into the mathematics of the origianl equation.

Yes, this is good thinking. Frquency modulation is the most common form of phase modulation, but not the only one. If, however, you want to pack more data in you need to employ a variety of methods, in multiplexed mode. This is how television tranmission used to work, before digital. Current so called broadband internet signals also use multiplexing, in this case time domain multiplexing.

Study this, it is applicable to fractals. https://en.wikipedia.org/wiki/Hausdorff_measure https://www.google.co.uk/?gws_rd=ssl#q=hausdorff+measure

That was the purpose of this thread - Spreading the Good News. Malicious code needs to spread to be worthwhile to its originators. We can all collectively fight this by broadcasting the antidotes.

This thread was meant as a warning. Even the most competent can be caught out. Yes you can do some of these things if you feel competent, but there is code associated with the link in some cases and as Sensei +1 points out simply arriiving at the link address from your own IP is useful information to a hacker. If you feel competent and want to investigate, you would be safer taking the address to a public net service, they are free in the EU and UK, and protected by a reset protocol such as Deep Freeze. We should all work together to combat those who subvert innocent folks.

Received this Email, this evening Please be aware of this scam as it is highly realistic. Except for the fact that PP have never had the particular email address they sent it to.

I hope you are right, but fear otherwise for the underlined bit. http://www.scienceforums.net/topic/107448-viruses-ransoms-trojans-spys-and-other-malware-into-corporations/

What is clear from this quote is that r x p is not a fundamental definition of angular momentum in the eyes of the author, since it is specified as being only applicable to a point particle, and nothing else. So there must be a more comprehensive definition which includes the angular momentum of thigns which are not point particles. I also note the linked Wikipedia of point particles which clearly indicates that r = 0 for a point particle and you so rudely denied. You were offered, and declined, convivial rational discussion at this more fundamental level.

Thank you Several of my former clients were retired university lecturers who undertook A level marking for some extra income. Most have since quit in disgust in disputes over unsatisfactory marking schemes and model answers, not to mention the online antics with computer based inputting. (Did you see that recent question here as to why everything needs to be online?)

I looked in the back of my cupboard and found one remaining olive branch I had overlooked. As I understand the situation You think you have discovered some circumstances where conservation of angular momentum is not true. I agreed with you there are such circumstances. So I tried to explore these circumstances with you. In fact I put substantial effort into this. But as far as I can tell from your minimalist responses you were not interested in such a project. I will make one comment on your assertion that the equation L = r x p is a definition of angular momentum. It is not a definition, it is is a very simplified formula for calculating the angular momentum in some circumstances. So I will leave you to consider my morning cup of tea that I have just poured. In order to stir the tea into the milk I pour the stream of tea into the cup along the inside of the cup. Thus it has linear momentum as it leaves the spout and enters the cup. But it has zero angular momentum. As the tea enters the cup it swirls round and ceases translation (the cup does not go anywhere) But in swirling round it gains angular momentum but looses linear momentum. So we have an everyday system that starts with all linear momentum and ends with all angular momentum. So neither are conserved since linear momentum is destroyed and angular momentum is created. Do you wish to discuss the analysis of this real world situation or do you wish to close the thread?

Yes I saw this morning when I opened your spoiler that you had reached the 3D conclusion before I did. I don't know if this was obvious in the textbook (for instance a chapter on 3D trig). Also this question demonstrates the need for proper labelling of diagrams. If the pretty picture was a scan from the textbook I would take proper labelling over beauty any time. I think the authors were unduly lazy.

The only way I can make this work is to assume the pretty picture with the shading and no identifying letters is not a plane figure but a 3D picture of an internal corner. Labelling points A by angle alpha, B by angle beta, C at the top and O at the centre/ origin / internal corner. OC forms a vertical axis cut by plane CAB at C. Triangle CAO is a right angled triangle (at O) as is CBO, but triangle OAB is not. Thus triangles COA and COB are at right angles to the plane of AOB. Thus in triangle CBO y = h/tan(theta) This give three known angles and one side in triangle AOB, which can now be solved by the sine rule for d.

I suggest you ignore the right angles. So you can easily establish alpha and beta, giving the angle opposite d (call it gamma). This will give you d by the sine rule as asked for if you know y. To get y by the sine rule you need to solve the upper right hand triangle. Can you do this? I made alpha = 23.57818 degrees beta = 29.55192 degrees gamma = 126.86990 degrees