19,898 reputation
23673
bio website
location New England (USA)
age 52
visits member for 1 year, 4 months
seen 2 hours ago

I have formal training in physics, but tend to approach it very intuitively; I prefer estimation over exact calculation, principles over details. I believe many problems can be solved by making a careful sketch. Label your axes, and don't use insignificant digits.

I visit this site in the hope of sharing my enthusiasm and occasional insights with others.


1h
awarded  Guru
5h
revised Proper way to write the units to indicate that they include an offset?
added 877 characters in body
5h
answered Proper way to write the units to indicate that they include an offset?
6h
answered Uncertainty of approximately sinusoidal voltage measurement
6h
comment Do electrons get accelerated or decelerated by the atoms of the anode during X-rays production?
Interesting question. While the interaction with the electrons is more important for changing the total momentum of the incoming electrons (because the electrons are light, more momentum is transferred to them), the greatest acceleration can be achieved by interaction with the nucleus (sling shot around it - nucleus remains "still"). I think. But there are more electrons than nuclei so I suspect (but have no hard data) that they are the more important particle.
7h
comment Uncertainty of approximately sinusoidal voltage measurement
When you say "mean" do you mean RMS mean voltage, or do you mean to say "how far from zero is the mean of this sinusoid"? Do you know the frequency accurately (you say 10 periods and 1000 samples per period, so that suggests that you do...)
10h
revised How much air needs to be displaced to generate an audible sound?
added 190 characters in body
10h
comment How much air needs to be displaced to generate an audible sound?
@Ariser - in general a short "click" contains "all frequencies" (just do the Fourier transform) and will be audible - but the detectability will be much lower than for a pure and sustained 1 kHz sound wave. So I agree you won't hear a 20 uPa click. But that's not what we calculate for the parchment...
12h
awarded  Good Answer
1d
comment How much air needs to be displaced to generate an audible sound?
You seem to misunderstand my answer. In the top half I talk about the question of the vacuum; in the bottom half I just describe "motion of air" in general (in order to address the headline question), and the amplitude that gives rise to sound (a very small amplitude is enough) in support of the general assertion that movement on the order of the thickness of paper can make a noise. I never intended to claim that the speaker would be able to generate the sound of the disappearing parchment.
1d
answered Do electrons get accelerated or decelerated by the atoms of the anode during X-rays production?
1d
revised How to find the Kinetic energy of a quarter of a wheel?
added homework tag
1d
comment How much air needs to be displaced to generate an audible sound?
I like how you think in the first part of your answer but take issue with your "mass of the speaker membrane" argument. The membrane is only there to force the air to move in a certain way - the electrical current is adjusted so the movement is sufficient to create a particular sound pressure. As long as the motion (acceleration) of the surface follows a certain pattern, it will generate the same sound regardless of the mass of the membrane.
1d
revised Falling dominoes
general typos, clarity, correction of equation
1d
answered Falling dominoes
1d
comment Falling dominoes
It would be helpful if you could define the notation used. As written one cannot guess some of the symbols, and specifically I wonder how you speak of energy without the mass or gravitational acceleration coming into it... Can you dig a little deeper into the paper and explain more fully (links disappear - your question need to be able to stand on its own). I think this could become quite interesting...
2d
comment Do atomic orbitals exist in a fully ionised atom?
@tom - yes it does
2d
comment Do atomic orbitals exist in a fully ionised atom?
I think this is a deeper question than it appears - rephrasing: "when an electron is capture by a proton does it immediately assume a stable orbital?". I think the answer is "no" because there is initial uncertainty in the energy (Heisenberg) so you can't "know" that the electron is in the orbital.until some time has passed. Suggesting that people answering include that consideration...
Nov
25
revised Why does a cooling car engine crackle?
added 48 characters in body
Nov
25
comment Why does a cooling car engine crackle?
Exactly - a stick-slip phenomenon. That's what I tried to describe in my answer.