@JakeRose Your last integral is of the form $\int_{0}^\infty e^{-a (x-x_0)^2}\,dx$, which is very close to being a familiar integral
the last approximation to make is arguing that, under the conditions of interest, the difference between your integral and the familiar one is small enough that it may be neglected
Today when I clicked on Physics.Stackexchange tab on my chrome the site opened up normally but when I clicked on Ask the window the tab opened up saying “confirm your account” and then I saw that my account from P.SE was removed or something like that must have happened.
I was suspended from ask...
@YuvrajSingh... If you ever want to learn from other posts, just click "edit" to see how the post is formatted. That is how I learn(ed) how to do a lot on this site.
@Semiclassical ahh just seen your message. Gonna be reattempting later tonight. I can see the Gaussian, but not sure how to get the n under the square root from that fact?
trying to decide which way of creating dilute solutions of known concentrations is better for an intro lab:
1) determine how much solute is needed for each desired concentration and in each case mix with water 2) create a solution of high concentration and dilute appropriately
based on the lab notes, it looks like it's the second.
I would think #2 teaches the most useful skills anyway, since things like acids and bases usually come high-octane concentrations and get added to water to dilute them down
Ugh someone just said this to me in an online tutoring session:
I am just trying to get through the class my major will never rely on physics. Personally it has no meaning to me. Even before we started this my teacher said if you are not majoring under physics all this will be useless to you
I said While your major doesn't depend on the content of physics, you could still learn from it. I am sure in your own work you will need to understand the definitions of important concepts and how to apply them. How to take a problem, identify important concepts, and figure out how to use those concepts to come to an answer
(this is intended as an osmosis lab: place potato slices in beakers containing various solute concentrations. if the solute concentration of the potato > solute concentration of solution, then water will flow from the solution to the potato to make the solute concentrations match. so the potato will take on mass.)
@AaronStevens It's like the people who hate math and just complain based on the super general idea "I'll never use this!" You might not even apply it exactly like you do in a math class, but that's quite different than never using it.
If they actually said that at the beginning of the class, then I can't blame them for having that mindset after going through problems like blocks on inclines
Learning "physics" is nontrivial amount of effort, sure. But if you go into it learning "problem solving skills" then it is the same nontrivial amount of effort on the same material, but has payoffs later
@JMac Yeah... I just don't see why you wouldn't want to try and figure out how to get something out of it though. Like I don't study history, but if I needed to take a history class I would find a way to appreciate and learn new ways of thinking
@AaronStevens I had to take a whole years worth of history classes on the history of science and technology. I also took a course on Science Fiction in Film. Even when I thought "I won't need to know this"; I at least took the effort to try to take some interest in it... the way I saw it, the alternative of not caring and retaining nothing seemed more pointless...
But yeah, a teacher telling the students they wont need it amplifies the problem quite a bit, that's crazy.
@JMac Yeah. During this session on each problem, in the middle of me trying to walk them through a line of reasoning they just said "I think the answer is this. That is what I am putting". And I said "Honestly, that isn't fully correct, and I would not give you full points if I was grading."
To which they said what I first quoted
The question was "Use physics to explain why air bags help prevent bodily harm during car accidents". They said "due to the force of the airbag and release of gas it help prevent a major bodily injury."
@AaronStevens It's especially crazy because they even have a (presumably hired) tutor and they still don't care. I had the attitude of "well screw it I'm just putting that down" with some homework; but that was typically when I already felt comfortable and just didn't want to do homework because it was worth peanuts in my actual grade.
@AaronStevens do you think with some proper modification (either in this or a separate question) this part of the question might be answerable (as you say it's vague for now).
@JohanLiebert It is a tough one. You might need to specify a specific scenario, but just make sure it doesn't read like a homework / check-my-work problem
You might be able to answer your own question by actually doing that
Pick a simple system, and pick different axes to calculate torque about
Maybe you could start with a single particle falling near the Earth's surface
how does your choice of reference point influence the torque acting on the particle?
How does your choice of reference point influence the angular momentum of the particle as it falls?
Does it still hold true that the torque gives the rate of change of the angular momentum?
@AaronStevens I wanted to consider this qualitatively. Do you think it would be correct to say that the torque generated about an axis other than the axis of rotation is greater in magnitude?
@JohanLiebert Maybe? I would have to do more thinking. For simple objects that just rotate about the same axis with torques always being parallel, perhaps. In general, I am not sure
@AaronStevens actually I wanted to qualitatively differentiate between an arbitrary axis and the axis of rotation, I thought about this for quite some time but couldn't get anywhere conclusive than this. Do you think I should modify my question to add this information?
@JohanLiebert I think a new question would be better. Your current question, at least to me, just seems to be asking if we can still use the definition of torque if we pick an axis that is not the axis of rotation
If you want to explore how that effects the analysis of a certain system, I think that should be a different question
But I would suggest picking a specific system to look at...
I recently asked this question:
What is meaning of torque about an axis other than the axis of rotation?
In the previous form of the question I asked the following:
How would the torque about the axis of rotation differ from any coordinate axis other than the axis of rotation?
I discussed...
@Loong If I know the magnetic field strength of a yoke is 24.435 Tesla. How do I find the pulling or repelling strength based on the magnetic field measurement? I need to know this so I can weld a yoke together. And know if the iron plate thickness needed to saturate the magnetic field entirely will hold up against the force.
@Loong Or if I need a different material with more strength. The pull force\repelling force will tell me what I need to know
@Loong I'm making the magnetic field with permanent magnets then a cone on the top of the magnets to make the magnetic field intensity greater.
I asked this question last night and it was closed as a duplicate earlier today, because it is similar to another question (this one).
However, the (apparently automatically generated) closure note states the following:
If this question doesn’t resolve your question, ask a new one.
As far ...