Recent content by ln(

This implies C = +1 which seems right. But how do you calculate C eigenvalue directly?

The C-parity of π+ π- alone is simply (-1)^L, where L is the angular momentum quantum number for the system. But then what is C-parity of π+ π- π0? Is it simply (-1)^L (+1), where L is the angular momentum quantum number for the π+ π- subsystem (which isn't necessarily the angular momentum of...

In this derivation of the Ideal Rocket Equation (https://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation#Most_popular_derivation), they use the fact that ##V_e = V - v_e##, or that the velocity of the exhaust in the observer frame ##V_e## is the velocity of the rocket ##V## minus the speed of...

But, for instructive purposes, wouldn't the field of case 2 be half their answer? I get this with ##E(2\pi r^2) = \sigma \pi r^2 / \epsilon_0## using a gaussian cylinder extending above the thick plate to below it.

Slight aside: when calculating ##\sigma## here, is this ##Q/A## where ##A## is the area of one side of the sheet? Or does this include both sides together? What I mean by this is: if a plate contained 4 C of charge, and one face of the plate was 2 m^2 in area, would ##sigma## equal 1 or 2...

Homework Statement Find the field at A. Homework Equations ##\oint E\cdot dA = Q_{enclosed}/\epsilon_0## The Attempt at a Solution My first intuition was to do a Gaussian cylinder from A to the middle of the bottom plate. My logic is that the field inside the bottom plate is 0, so I'd have...

So then shouldn't the question ask for a maximum displacement rather than a minimum? If pushing the ruler down too much projects the mass up into the air.

I see. So then we are looking for the top of the oscillation to see where the "barely loses contact" condition is relevant. In the model, this is ##x## above the equilibrium. For the ruler, this corresponds to ##A## above the equilibrium. And I know how to solve for ##x = mg/k##, and this...

The question says that the mass-ruler system is released after being pulled down by a distance ##A##. I understand how the model in post #2 works, but the mass isn't simply being released here. I also don't understand what you mean with your second point. My understanding is that if you don't...

The elevator accelerating downwards with ##a > g##.

Yes. But how is there a "minimum initial displacement" for that? Wouldn't it lose contact if the mass has non-zero velocity at the top of the oscillation?

##F_N = 0##?

The period, of course. So now I think we've established that a simple spring system can be used here as a model, since it says SHM. But I still have no quantitative understanding of the "barely loses contact" condition.

Well then it would also be ##g## wouldn't it?

The equilibrium position here isn't parallel to the table, correct? Because the ruler has mass itself and the equilibrium position should be be at some angle below the horizontal. Just checking my understanding. So then, wouldn't it descend ##x## below the equilibrium before bobbing back up? The...