studiot

Good to see you in action again, Eise. Welcome back. It is always a pleasure to have your clear thinking in a discussion. +1 and yet You various examples assume that there should/must (since the imperative is used) be one and only one capable of dealing with a given phenomenon. One of the principles of modern science, technology and general work practice is the principle of independent corroboration or check. That is arriving at the same result by different routes. Another example of differnt routes lies in the difference in the way a modern computer reaches an output versus the way a human migh do this. The computer takes lots of small simple steps but very quicklyso that the computer can arrive at a result in milliseconds that woud take a human a whole lifetime to reach by the same method. Further examples occur where a method we know to be theoretically unsound, arrives at the same result as the more complicated and long winded 'proper' method. For instance the method of virtual displacements, D'Alembert's method etc. Perhaps @Col Not Colin was getting at this sort of thing in his post ?

I have absolutely no idea how this would happen, but isn't that exactly what the word condense means? Isn't that what happens when a gas condenses to a liquid or a liquid to a solid ? A new form of PE is aquired - surface energy.

Unless the cloud can convert KE to PE somehow, since temperature is a function of KE, not PE don't you think ?

Wasn't Ok a junior member of an american religous sect ? Or did you mean the traditional scots greeting OK Hamish ?

What you are doing reminds me of the man who said "I am trying too make a walnut into an oyster, both have a hard shell in two parts with something I want inside. Since they are 'kinda' the same I should be able to grow pearls inside a walnut"

Actually he just did, take note and learn.

Why Wilhem of course. https://en.wikipedia.org/wiki/Killing_vector_field

It was a new one on me and it means something different from a prologue which is meant to supply background information to the text, without criticism or appraisal. Prologomena (p) and prologomenon (s) include some form of appraisal or criticism. I am sure you are awae that Joigus didn't mean that, but used arbitrarily in its correct technical sense. A really good one-liner there. +1 One thing about simple principles is that we have a natural tendency to abstract a single simple principle and then try to treat it as if it were an independent variable, whereas often the variables are not (fully) independent.

Guesswork is a very inefficient method of learning at the best of times. The less solid and more hocus pocus the background you base your guesses on the more inefficient it becomes. It is no accident that the initials of Harry Potter are H.P. Who is the kid and who is teaching him ? Where do they teach magnetic cooling to kids in Physics ? Electrostatic traps work on ions not atoms. I wonder why ?

The Subtle Knife is book 2 in Phillipp Pullman's fantasy trilogy 'His Dark Materials' I expect your students can tell you all about it. https://en.wikipedia.org/wiki/His_Dark_Materials The Ockham quotes came from the prolegomena (what a word!) of Variational Principles in Dynamics and Quantum theory By Yourgrau and Mandelstam An interesting mixture of the Philisophy, and Mathematics of the Calculus of Variations. Sleep well.

This is a prime example of why you should stop guessing and listen to some very knowledgeable person who has the patience to listen to you. Alternatively you could actually read a textbook and find such things out for yourself. +1 for your patience.

Good question, how many giant's shoulders are our assumptions standing on ? +1

Not at all. You picked out a clear cut case where the 'obvious' simple explanation is incorrect. The actual reason is more complicated. In the OP I am posing a discussion question, has the razor been superceded by modern science ? My answer is obviously therefore yes, since there is at least one case where it is unreliable. But it is a good discussion and it is my hope that when (new) members produce outlandish 'theories' and say it must be true because of Ockham's Razor this thread can be pointed to as evidence of that unreliability.

If the air pressure inside the balloon was not marginally greater than the air pressure outside the balloon would collapse inwards. Since the pressure is greater, the density must be greater and thus the mass of displaced air is less than the mass of the air inside the balloon, even without the basket and trappings. This is different from a rigid balloon such as a hydrogen or helium one where there is a positive bouyancy force.

Are you saying that the razor suggests Archimedes principle - which is of course an incorrect explanation ?

Carry on ?

Like Pullman's Subtle Knife perhaps ? Thank you so much for introducing a modern area of statistics I had never heard of - off to investigate! +1 Since you are interested his actual words were Which translates as It is futile to employ many principles when it is possible to employ fewer. But he did not say that the extra principles are untrue and all too often it is used as an excuse to reject the (more) complicated, whether justified or not. We are all a bit lazy and like to use the excuse "neglecting (higher order) terms as insignificant" This applies to my favourite engineering formula "something squared over twice something else" , which is not validated by the razor but by mathematics. But I would love to see the razor applied to the theory of flight of eg a human made mechanical aircraft, a butterfly, a hummingbird and a hot air balloon.

Translated this reads Things should not be multiplied beyond what is required. Yet no one has found this exact text in his writing that survives. It is true however that much of his writing echoes this sentiment. Howsoever it maybe the question is as in the title How true actually is it ? I posted this because members often appeal to this maxim for support.

So how is it 'confined' ? In MRI the water is confined within the patient. What do you think the R stands for in MRI PRI and NMR ?

That is not my understanding of the working of MRI or othr NMR machines, nor how it is described in your link.

We don't do you homework for you some of us help you to do it ! It is important that you work through as many convertion examples as you need until you can 'do it in your sleep' . There is no other way to proficiency. Please note that new members are only allowed a total of 5 posts in their first 24 hours, to help prevent spammers. After that you can post as many as you like. Go well in your studies.

Note you can use superscript on this forum Scientific notation usually means a number between 1 and 10, for which we don't write the power of 10. So strictly your answer to should be 1.5 μL However many scientists also allow or just write 20 as just 20 not 2 x 10, So they are choosing numbers between 1 and 100. Engineers use numbers between 1 and 1000 and that is the basis of using only milli and micro and kilo.

OK thank you it was in biochemistry. And it was one of many general practice questions. I asked about pharmaceutical calculations because some medicines are supplied as a particular mass in a vial to be diluted and then added to an infusion bag of particular volume. Such questions would be almost in the format of mass to concentration by volume. And there was a slip up with question 5. So check that no addendum was posted and inform your academic supervisor. Chenbeier was correct. +1 For others who might be interested here is the excerpt from the pdf.

No, please post the complete correct question. Then we can help you with your units. You have posted in Chemistry, is this in fact a pharmaceutical calculation and is it coursework/homework ? +1 to Col for attempting to help.