Recent content by Pi-Bond

But if the tensions are perpendicular to their radial vectors, how can they have a radial component?

I'm unsure about how to get the radial component of the tension. Anyway here is my understanding of the geometry of the situation: Is this correct? FT refers to the force due to the tracks. The centripetal force required by the car is \frac{MV^2}{R}

Oh sorry, I wrote the wrong formula in haste. What I meant was F_5 = \frac{F}{5} F_4 = \frac{2F}{5} and so on. Also I noticed I didn't say that we have to find the velocity for which the rails exert minimum force on the central carriage. Sorry about the confusions. So in order to...

Homework Statement A train consists of a locomotive and five identical carriages, connected via massless ropes. Initially the train is moving at a speed V. At this speed, the tension in the rope, F between the locomotive and the first carriage exactly balances the resistive drag, so the train...

But in the first case, one branch of the parallel circuit has two resistors of σ+ and σ- in series. In the second case one branch has two σ+ resistors in series, while the other has two σ- resistors in series. Why this change?

I figured out the answers. For the first part, both branches had the two resistors of either conductivity in series. For the second part, one branch had the two resistors with σ+ in series, while the other had the two resistor with σ- conductivity in series. I'm not sure why this is the case...

So are resistors on one side of this parallel geometry having the same conductivity? By the way this is from a comprehensive exam. Sometime we do see "historical question", but the effects are not really named!

Do you mean something like this?

Homework Statement Electrons in a ferromagnet whose spins are oriented in the direction of, or opposite to, the internal magnetisation carry independent currents I+ and I−. This leads to the material behaving as though it has different conductivity σ+ and σ− for each of the two current...

All clear! I understand better now, and I will keep that expression in mind. Thanks mfb!

I am seeking resources that cover the Mathematics of Quantum Mechanics in order to prepare for an exam. The course is not rigorously mathematical, and as such, I am looking for materials comprehensible to the average Physics student. Websites, books, online courses/lecture notes are all...

I don't see how...assuming the expression is true E = \frac{pc}{\beta} = \sqrt{(mc^2)^2 + (pc)^2} I haven't really seen this anywhere. Anyway, are the products moving in the same direction in the galaxy frame? (as neither have any momentum in the zero-momentum frame)

Indeed, its not needed to prove the expression, but the question asked for the two conservation expression in both frames. By β are you referring to v/c? I was thinking of using the "mass shell" formula.

So the identity they want can proved as E_{HE}E_{CMB} = \frac{\Gamma}{\Gamma} E'_{HE}E'_{CMB} = (mc^2)^2 So I have got all the equation except the momentum conservation one in the galaxy frame. I guess the photon momenta can be obtained by p_{HE} = \frac{E_{HE}}{c} But what about the...

So is E_{CBR} = \frac{1}{\Gamma}E'_{CBR} and E_{HE} = \Gamma E'_{HE} ?