studiot

Deacon, a good solution, but don't you think it a tad explicit for homework help?

I have also answered this. It is not I but the regulations you posted that specifiy the gloves. Yes, as you said, it was the interpretation of an old and very well repected University Chemistry department, no doubt assisted by a very able legal department, The department of Chemistry at the University of Leeds. There are you satisfied now?

Yes, I did. And you are right, they do tell you that gloves should be suitable. That's why I posted them. Why did you post something that doesn't say that gloves must be suitable? Do I have to answer things twice? I do take your point about the eye protectors, but it may well be the case in that lab, as in all school and college labs these days, that eye protection is mandatory at all times so not specifically included in any instructions specific to one experiment. So the eye protectors may have been there as a general precaution. Wouldn't it just be so much easier if post numbering was reintroduced?

Presumably you also have something to hang the device from or stand it on or tie it to? A good way to start would be to make a list of exactly all the things the device must do (and not do) in sequence as the egg is dropped into or onto it. Then you can talk about each one of these separately to make them happen.

Gosh John, did you not read the regs you posted? Gloves are classed as personal protective equipment, so perhaps you should ask your granny about the suitability of her gloves. Did you read the instructions I posted Specifically it does not say that. The COSHH assement specifically says you should dispose of the acid in a fume cupboard. Although As to the use it says "add 10 drops of the acid with a pipette. It does not say "pour out the acid from a bottle into a test tube." We still don't know why the girl was doing this or, in truth, a good deal more about the circumstances. I am more concerned about the circumstances that lead to the incident, than the incident itself which could have been more serious, and points to insufficient supervision IMHO. The girl may also have more sensitive skin than you do, or did at her age. When the students come to use a large volume (stil only 50 ml) of the acid they not a small test tube. I do take your point about the eye protectors, but it may well be the case in that lab, as in all school and college labs these days, that eye protection is mandatory at all times so not specifically included in any instructions specific to one experiment. So the eye protectors may have been there as a general precaution.

Indeed yes. Here are the relevant UK regulations Control of substances hazardous to health or COSHH regulations. https://www.chem.leeds.ac.uk/fileadmin/user_upload/yr12_practicals/Y12_Inorganic_2016_Final_version.pdf

Looks like she had a lucky escape. Has anyone put some cream (eg Nivea) on it?

Did your daughter scratch at the site of the splash? Not a good idea as that would rub the acid in. You didn't say if the teachers immediately washed tha acid off? Or did someone just wipe it off and then leave it? 1M is not that strong for a near adult, but what was an 11 year old doing with it and what was the supervision? By way of contrast car battery acid is 4M to 6 M and would definitely burn straight away. Here is a company Health and Safety document which regards 1M as "corrosive to skin" http://www.onboces.org/safety/msds/S/Scholar Chemical/Sulfuric_Acid_1.0M_740.00.pdf

Get hold of this book http://press.princeton.edu/titles/8861.html It exactly fits your bill. BTW Sears and Zemansky have various books that are streets ahead of the Resnick & Halliday, even as edited by Young and Freedman.

Your are too suspicious. I am trying to work through the physics of something with you so that that you can see for yourself what the facts are. It is fundamental to wave theory that a point source produces a spherical wave that spreads out in all directions. So a point source on the surface of the Sun (Point P in my fig1) creates an expanding spherical wavefront as I have shown dashed in Fig1. This has an average radius of 150 million kilometres by the time that front reaches Earth. The source at P does not have a choice in this, nor does it have collimators or focusing devices. But yes there are many such sources on the surface of the Sun and they are not coherently phased, like a laser. (Thank the Lord Huygens) or we would not be here if they were. I said that as a result of that distance that wavefront is effectively a plane wave so the (very simple) maths of this is shown in fig2. The deviation of a circular curve from a straight line is given by the formula (distance along the straight line squared) divided by (twice the circle radius) With the figures shown this works out at about one tenth of a millimetre over the linear distance of the radius of the Earth. So think how much straighter the wavefront must be over the size of a carbon dioxide molecule, whose bond lenght is 1.16 x 10-7 millimetres long. This is why we can say that in another model - that of geometrical optics which treats light as a series of 'rays', that the rays from the Sun are parallel. I mentioned bond length of carbon dioxide which is important because this determines the frequencies for the four fundamental modes of vibration of the molecule. The plan is to fully understand how a straight radio aerial works and see if we can use this to understand how the stretching modes of the carbon dioxide bonds comes to be in the IR and microwave bands and not other bands of the EM spectrum. But first we must look at your thoughts on how a radio aerial actually works. This is not far off the truth but just need a couple of amendments. I have underlined the relevant bits. Firstly and most importantly. Forget resonance - the word will get you into trouble when we consider charge separation in the carbon dioxide molecule. It has a specific and quite different meaning for chemists and bonding. The radio waves induce current in any conductor of any length. Resonance is not required. The issue is what happens to those currents when they have been induced. We shall see that conductor length then becomes vitally important. I prefer the phrase charge separation, rather than current because that is what happens in both the radio aerial and the carbon dioxide molecule. The effects are potential driven, not current driven. Finally we spoke about reflection, absorbtion and transmission. What about refraction and diffraction of waves? I think we are doing well and making real progress

I agree with iNow - to quote the old phrase "There's none so blind as those that won't see and none so deaf as those that won't listen."

Surely if he admits it doesn't have to then you can challenge him as deceitful. Ask why did he use something he knew to be false as a challenge, instead of offering proper evidence or reasoning.

Nor am I a biologist, but why does the genetic information have to increase? Why can't it simply change but stay the same quantity? Or heresy even, diminish if a trait is lost or dying out? BTW how does one measure the quantity of genetic information?

I like miracles. +1

Actually I'm very much against Hinkley C - it is a complete and enormous waste of public money, when there are much better options available, whcih are also 24/7. However the point about both solar and available wind is that they represent low density energy with substantial off periods. (With apologies to those in the Americas and Asia suffering from more powerful winds) You are close enough to Cruachan to understand the obvious implications of what to do about that.

Not on the solar panels I am familiar with, and not when there is no Moon to speak of.

I have it! There are (or used to be) certain radio /TV call-in shows where the presenters made a specific point of insullting or brow-beating the callers. The OP has escaped from radio GAGA where he was trained in these darkside arts. May The Force be with you all

Does anyone know what happened to Mitch? Seems strange that he would ask a question and not bother to come back for the answer.

I find it very comforting at night when I want to turn the lights on, cook my dinner and watch the BBC, that nuclear is constant, unlike solar.

So far you seem to think that there are three possibilities (though not mutually exclusive as with your chlorophyll example) when light approaches something. Transmission, reflection or absorbtion. That is not the case. Do you think that the radio wave is transmitted through the solid copper bar of the aerial? We have just agreed that the wave appears on the downstream side of the bar (it is not blocked by it) Having agreed that an aerial is frequency selective, do you understand how one works? I suggest you forget photons here. I have already suggested that for the purposes of this thread and your on topic question classical wave theory is adequate. I agree that there are many additional observable effects that require alternative theories, but they are not on topic here. Directionality is a not function of the wave alone, it is also dependent upon the source. The issue of a propagation medium is off topic here, but I would just observe that Faraday's notion that the wave generates its own medium as is goes along is adequate here. Finally your response to my observation that waves are larger than the obstruction leaves much to be desired. If the waves are propagating in the z direction then they are enormous in the x and y directions since they are so far from the source they are effectively plane waves. The 'waves' of light from the Sun are vastly bigger than the Earth itself. Hopefully you understand this much.

You have more faith in electronics than is warranted by my (passenger) experience of controlled rail systems think is warranted. There is a wonderful scen in the Norman Wisdom comedy where the hero is put into a centrifuge to practice Hi-gee. He is shown the safety cut out button to press if the stress gets too much. When they finally decide to stop the machine and drag him from it, they ask "Whys didn't you press the safety button?" He holds out the button with its connecting lead broken off. "I did" As to efficiency the figures were in the last post. The eurostar hauls around a ton of metal or more per passenger. Trams are no different. You can get 4 or more people in to a car that weights 1/4 to 1/2 ton That is one of many reasons why they are more efficient. The tractive effort of tyres on the road are also inherently more efficient than steel on steel. And of course you have to allow for the inefficiencies of generating that electricity for the tram motor.

Taken as a whole, trams (and other rail systems) are considerably less efficient than small IC engine cars. The price of lowering pollution is a reduction in efficiency. They are not necessarily safer either. The recent incident of the crashed Croydon tram on its side amply demonstrates that they can have bigger accidents. A few facts and figures: A single Eurostar train takes 800 passengers It weight 800 tonnes Putting all those passengers in cars would occupy 800 yards of the M25 London orbital motorwaY

https://en.wikipedia.org/wiki/The_Roads_Must_Roll

https://www.amazon.co.uk/Shorter-English-Dictionary-William-Trumble/dp/0198605757 Only £63

That is the shorter version, note the page number for the letter m. But is really is a good book. No I would not use a hyphen like that, although Americans do and it makes spell checkers a real pain. I might use the hyphen to separate two vowels say in re-edit, but not in remagnetization, it serves no pupose there.