studiot

Perhaps you should tell Mark that? The table appears in 'Mark's Handbook for Mechancical Engineers ' as table 3.2.4 though I would have thought by the tenth edition someone would have already pointed that out if it were untrue Mark's is, of course. the 'CPC Handbook' reference for this field. There are some interesting notes and other tables, however, since conditions such as the presence of surface films make a big difference. Table 3.3.3 lists Friction for Steel on Steel dry 0.78 Oxide film 0.27 Sulphide film 0.39 Friction for Copper on Copper dry 1.21 Oxide film 0.76 Sulphide film 0.74 Engineers should learn to read the correct table correctly. You may have been thinking of the data from the oxide tables. Mark gives further data for specially ground harder steels that reduce these values even further.

Isn't that like the detective asking the suspect to admit to murder, why would he? and why would anyone admit to promoting a theory that "does not stand up to scrutiny" Pope was not the only poet quoted here. Coleridge was also an accomplished mathematician and wrote a very famous letter to his brother about it.

Yup that's it. This one was really too easy, compared to the last one.

What happened to the overheads?

No need to be sorry. Ratio and proportion puzzles many people, but we got there in the end and you did most of the work yourself. I'm glad to help anyone prepared to put the effort in.

My post#6 was meant to stimulate questions about your integration. I don't see a logarithm creeping into your working and there should be. What is the integral of a constant times dx and what is the integral of dx/x ? Note I haven't cheched you separation of variables to see if you got the original fraction correct, fuzzwood already asked you for that and I don't see that either.

Well I was considering reporting the downright rudeness of 1) Not replying to my questions (which were about your request) 2) Posting deliberate nonsense ("Doesn't mean anything sir") I seem to have wasted my time and effort on your behalf.

Thank you for the link, I will give it a try [math]\int \frac{a+bx}{cx}dx=\int \frac{a}{cx}dx + \int \frac{bx}{cx}dx[/math] Yes it works in one hit and the code seems simpler than MathType produces. So perhaps that (expensive) program will turn out to be a waste of money. +1

Well I don't know the difference between these options To post the three integrals I had to split the equation in three parts and post the LHS, the left integral on the RHS and the right integral on the RHS separately. If have no idea wht the system 'renders' the latex to. Each segment of latex code was produced in MathType and pasted as MathML. When the first attempt including all three integrals in one go did not work (in the simple reply box) I first went to the more reply options to see the preview and played with it until I beat it into submission, I first split it into two segments, RHS and LHS of the equals sign, which was written in ordinary text. When the LHS displayed, but not the RHS I split the RHS either side of the plus. That time it worked.

I would be very happy to learn more, though I suggest you hive this off to another thread, with a link left in this one, since it can be a real struggle to post a simple bit of maths like the above examples.

Thanks, imatfaal. I see the faint background now you mention it. To the OP, it is counterproductive to post insufficient information/description, if you are serious about it. All you achieve (as here) is a group of other baffled posters asking what you mean, instead of being able to get on with the discussion. Useful information would be what is the (approximate) date of the picture and where is it to be found? What material is is painted? inscribed? on?

That's jolly spiffing for those who speak fluent latex. Lingually challenged members like myself copy and paste from a formula editor. I find however that the renderer (is that the right word) can't chew even moderately complicated formulae so it is necessary to paste in sections either side of a normal equals or + or similar sign. For instance this would not take in one go but pasted OK in three sectrions, all enclosed in math tags as already advised. = +

Maybe I'm thick, but I have no idea what you mean.

I don't follow this?

http://en.wikipedia.org/wiki/Pentomino

Dominoes or penrose tiling of some sort?

Yes it does. Well done you have produced a different method than mine for both parts of this question, although I hope I have helped. +1

Really? Then I would say it is pretty good. This table from the International Handbook of Mathematical, Scientific and Engineering Formulas, Tables, Funtions, Graphs, Transforms (Fogiel) makes interesting reading There are also extensive tables of special conditions that can reduce some of these towards 0.1

Yes this is perfectly true and you have already used it (indirectly) in solving the first part of the question to get to the 50 days. The original fraction I wanted and why I said Now you found a and have to find b. Since A completes the task in 50 days If B completed the task in 1 day he would be 50 times as fast. If he completed it in 10 days he would be 5 times as fast. So B is a/b = 50/b times as fast as A Which of course means that if b =50 (it does not) the B is exactly as fast as a since 50/b = 50/50 = 1 This ratio or fraction is important because it connects B's contribution to A's contribution so that we can add them together as the next step.

If you can explain it better, please do, you are welcome. But please don't disrupt the thread.

Can we go we the idea that if C works twice as fast as A he takes half as long?

Surely it would take B 15 days to do 15 days work? This is not much better than your last comment, which I pretended didn't exist. Just bear with me and follow through what I have already said and we will get to the end.

Well I like this bit.

OOh, can I make a bid of $0.00 (disallowed) for one?

Looking at the end of your working surely [math]\int {\frac{{a + bx}}{{cx}}} dx[/math] = [math]\int {\frac{a}{{cx}}dx} [/math] + [math]\int {\frac{{bx}}{{cx}}} dx[/math] Where a, b and c are constants. is a very basic integral