Recent content by tomz

May you shed some light on this? Or quote any possible reference? Thanks

Am I making the mistake of ignoring the tangential component of forces... Thank you so much!

Thanks for the reply. Sorry I did not make it clear. I mean for a vortex, or any flow that is not along a straight line. Because from what I deal with viscid fluid/statics/pressure vessel.. when there is rotation or cylindrical coordinate, we tend to use a curved shape (sector)...

Dear all I am having a problem on circular flow of fluid. On all books I have read they say \frac{dp}{dr}=\rhov^{2}/r Which make sense by using infinitesimal square volume and take the force exert. But if I use a circular infinitesimal volume (which is usually the case for circular...

I am a new starter on thermodynamics, here is my question.How does a throttle work? I can understand the equation behind throttling process, how enthalpy is conserved...etc But I cannot understand how throttle actually achieve the decrease in pressure? is it through turbulent the flow...

On my textbook, there are several definition given for this Q factor. 1) 2 pi * maximum energy stored in reactive element / energy dissipated in a period 2)resonance frequency (in terms of ω) / band width 3)Q = 1/(2 * damping factor)I have tried a couple of random circuits, and its seems not...

Thanks. After some thinking I guess there is also the problem that not all electrons released have the theoretical maximum energy, so the potential get from a voltmeter will be biased

Hello When we try to find a formula for time dilation, we think of a situation where the velocity of the other frame is perpendicular to the velocity of the light (http://en.wikipedia.org/wiki/Time_dilation) Why is this? I know if we try any other direction there is length contraction...

Hi everyone, a quick question on photoelectric effect. Why measure stopping voltage by connecting a battery to the circuit and then adjust until current reach 0? Cant we just use a voltmeter? Thank you!

Hi everyone, I have a very simple and classic question here. Suppose I have a 10cm,0.01kg ruler (uniform density) in space. And I apply a 1N force 2 cm from the left end of it. What happened at this instance? I guess centre of the ruler will start to accelerate as a=F/m=100ms^2. But what...

Thank you!

Hi everyone, I have a question here on what cause doped semiconductors to conduct. (such as Silicon with some As present, this is one atomic number higher) On my chemistry book, it says As covalently bond with 4 Si atoms as Si does, so the lattice is preserved, and 1 of its valence electron is...

Hi, thanks for reply... I think I have understanded what you say. Thanks

I thought this tension is tangent to the surface... people say water surface is like an elastic sheet..

Thank so much for the reply and the picture... I guess I have made some progress... Maybe I should look more carefully into the word 'tension'. By the way, do you mean that in the liquid, neighbour molecule actually develop repulsion force, but molecules further will develop attraction force...