studiot

Go , how?

Since you mention concrete, this is a good subject about which to discuss statistics. Let us say you are in charge of a concrete production plant outputting 2500 tonnes of concrete per day. How do you make sure the concrete is up to specification? I should tell you further that the concrete is particularly high specification, because it is to provide the runways for jumbo jets to land on and failure of substandard concrete could lead to landing accidents with subsequent loss of life and runway functionality. This is a real world problem I have faced, and met with success, in the past, with proper use of statistics to help me.

In research, yes. But with the greatest respect, in the quality control situation we have been discussing there is no room for art or pattern recognition. A batch of product either falls inside or outside of the quality control limits, as calculated in a particular way. This twist in the tail is more important than might at first appear.

Perhaps you have a poor maths (statistics) teacher. A good strategy would then be ask lots of questions about the whys and wherefores, rather than branching out on your own with what appears to be an attack on statistics itself. I would agree that there is a great deal of poor or even false statistics about. There are even books, radio and television programmes about that very observation. But neither poor teaching nor poor practice invalidated good teaching and practice.

Perhaps you are new to discussion forums. So this is meant to be helpful. Each time I have extracted the part of your post I wished to discuss and put it in a light blue quotes box. Exactly as I have done above these words. Then I have made my point about this extract. Consider the following: A manufacturer of medicinal pills requires to have just exactly the correct amount of the correct drug in each pill. So what to do? There is only one certain way to ensure that every pill has the correct amount of the correct drug and that is to test each and every pill. Unfortunately testing destroys the pill. So having tested his pills to perfection the manufacturer finds his patients dying for lack of pills, since they were all destroyed in the testing. Alternatively the maufacturer can test some of the pills and hope the rest are correct. But what does he do if they are not? And how certain can he be if the test pills are OK, that the rest are OK. That is precisely the situation I meant in my first post for the proper use of proper statistics.

Yes, of course you can use your formula. But not all future questions will be the same so I hope this thread has helped you understand more. In answering questions I find it a good idea to list all the information provided as we did here and then list the equations that might be relevant and see how they match. Go well in your future studies

You made definitive statement, I addressed it by asking a question.

I like to try to keep things simple and address one point at a time. I asked a very simple question in my post 4. What is a very simple answer, please.

With no acceleration, that is constant velocity. Distance = velocity x time s=ut; initial velocity ( = u) = final velocity (=v) If there is constant acceleration ( I will use f for its symbol) then we have sevaral formulae, you should have met before reaching the formula you quote. v = u + ft s = ut + 0.5ft2 v2 = u2+2fs The first two contain time, which we do not know but the third is the equation I was asking for. Now the acceleration (f) = g, u = 0 and s = 3.6 So substituting we have your formula v2 = 0 + 2g (3.6)

Voila you have u=0, s=3.6, What is the acceleration during the whole of the downward journey from A to the water? And then we return to the formula I asked for in post6

And if I could prove the opposite, without mathematics?

Voila you have an initial velocity, u=0. Now can you answer the how far questions?

Is this your answer for my question1? Which direction is he travelling from the diving board to point A? Which direction is he travelling from the point A to the water? So what must happen to the velocity, instantaneously, at point A?

Well your diagram should look something like an upside down hockey stick over the diving board. Look carefully at this diagram and my list of questions in post 4. You should be able to answer the first four just by looking at the diagram. You only need one formula to obtain your answer (my question 5) from this information, not lots of them. Let us work through the firstr four and then think about 5.

Are you asking this as someone who understands proper statistics and its proper uses? Statistics makes for a better, safer world by providing quality control tools. There not even a sniff of a definition.

Have you drawn yourself a diagram? Do you know the formula for the final velocity, given the initial velocity, acceleration and distance covered?

Whilst it will continue to run once already running, an electric motor will not start without auxiliarly help. The purpose of the capacitor is to provide a phase shifted supply (That is the alternating supply is connected to bothe main winding and the capacitor) to a second winding that is used to start the motor. Motors often have centrifugal switches to disconnect the capacitor once the machine is running.

Sure, you must know some equations of motion under constant acceleration. To start you off I will redescibe what happens with annotated questions. The person jumps (which way) off a diving board. When he reaches his max 0.6m above the board 1) What is his velocity at this point? 2) What is his total height above the water? 3) What distance does he travel to hit the water? 4) What his acceleration? 5) what is his final velocity? Can you do the problem now?

Why is the thread title element 531, when you are referring to an alleged element 534 in your post?

You can connect any componeent to AC or DC but The interaction with any component is, in general, different for AC and DC. For instance a capacitor can pass AC, but not DC. However it can store DC, but not AC. As to switches and their ratings. You will often find the same switch with a lower rating for DC than for AC. This is again because of the different response (yes even humble switches have different responses). When a switch closes some arcing inevitable occurs. This damages the contacts by pitting. Perhaps you remember the old fashioned pre electronic ignition system of points in a car? If this passage of current is always in the same direction (DC) then this can lead to corrosion and enlargement of these pits and eventual failure of the switch. Continuous reversal as in AC does helps even out the situation. As a matter of interest Ask yourself 'What is the meaning of AC' and then ask yourself 'What, therefore, is AC current?'

Don't you also require carbon as well as heat to reduce iron oxides to iron? Iron will burn if you heat it hard enough, so I don't think heat alone will do it.

I don't think the story will be on the net, but here is something other than traffic news about it. Unfortunately it demonstrates all too well that you should not believe all you find on the net. This links say 'built in the 1990s' But my CV tells me that I was the senior engineer constructing the project from 1979 - 1981. http://www.sabre-roads.org.uk/wiki/index.php?title=Obridge_Viaduct

I'm sorry? You need to remove energy not add it.

Yes, I've seen that happen. The pig troughs (sorry parapet visual enhancement panels) on the Obridge Viaduct.

I have my doubts that it would ever be possible to perfectly preserve fracture surfaces and then exactly align them. However I seem to remember cold fusion bonding being achieved in ultraclean labs between two samples of suitable material. Not broken material, but specially prepared material. So that is probably the nearest we will ever get. Sorry I don't have a proper reference, but I will try to find one. And like I said there is the problem of the energy released. You do not want this to go into the newly formed lattice since this is exactly the right energy to break a bond. So it must be removed somehow.