Recent content by Davide82

Ok. I am understanding.

Thank you twofish-quant. I understand your point with elastic collision. It didn't come to my mind. But, regarding the second equation, I don't understand well what you mean... because of course the processes are related: for example the two processes: e^- + e^+ \longleftrightarrow \nu +...

But they in the very beginning are writing a similar reaction: So I believe these kind of reactions are considered, too.

I believe it is perfectly legal and it is simply a momentum/energy exchange which maintains kinetic equilibrium. I think it is like compton scattering, where a photon and an electron hit and particles type are the same incoming and outcoming.

And... I was a bit imprecise: Watts are a measure of power, not energy; but since energy is conserved and the draining from the outlet is taking the same time as the charge process, you can say that the power is conserved, too.

First of all I must say that I feel like you have a wrong approach at this exercise and maybe in general in your study. It looks like you are trying to put together all the data you have in some manner. I suggest you to understand much more the underlying principles. For example, in this...

As usual, the time needed to charge is t = C / I. The more the current the less the time required. With 1200 W of power available, how much current can you draw at 3.5 V? P = V x I; so I = P / V (just as in point (iii)) so I = 1200 W / 3.5 V = 343 A. So t = 1.05 Ah / 343 A = 0.00306 h = 11...

Sure! First thing to do: read very thoroughly the problem!

Power available = 0.7 W. Since it should deliver energy at 3.5V (because you're charging a 3.5V battery pack; in real situation the voltage needed to charge a battery is slightly more than the nominal voltage of the battery) we get a charging current I = P / V = 0.7 W / 3.5 V = 0.2 A = 200 mA...

By the way, this thread of yours seems related: https://www.physicsforums.com/showthread.php?t=425341

I really don't know what is the correct answer! I don't understand what are Cb, I, t... what is a "given" and what is the aim. In the first post you are looking for a time... BUT you write t = 378 minutes from the very beginning... (what is this time? is it the answer and you want to get it...

It is not clear what data you have from the beginning and what quantity you're looking for. If battery capacity is C = 1050 mAh and charging current I = 100 mA you can calculate the time required in hours with: t = C/I = 1050 mAh / 100 mA = 10,5 h. But I see inconsistent things: you say Cb...

Hi. First of all I apologize because I already posted this topic in the "Homework & Coursework Questions > Advanced Physics" but since it exquisitely concerns astrophysics and it is not getting many answers, I believe it's better to post it here. If a moderator wants to merge the two...

I am still digging... I believe the \nu + \bar\nu \longleftrightarrow \gamma + \gamma is forbidden by the model. The second maybe is not interesting because the other reactions already take care of the kinetic equilibrium of protons and electrons. Since these reactions are brought up to make...

oh, now the first post with TeX has been fixed!