Before posting anything, please review the Physics Forums Global Guidelines.
Again, for some odd reason, people...

Apr2211 05:26 AM
ZapperZ

1 
41,737 
Why cant two field lines intersect? The answer that i have often heard is that if they were to intersect, then there...

Oct1012 07:12 AM
mikeph

13 
1,940 
I bought a compass today. I tested it at the store, multiple times, spinning all which ways. It would always...

Oct1012 06:55 AM
Borek

7 
1,013 
Hi,
I would like to calculate the sum of momentum in the blue volume. See drawing. The blue volume is full of...

Oct1012 03:50 AM
Gh778

17 
1,206 
Hi all,
I've been trying to understand the vibration of a cantilever beam subjected to a forcing function using...

Oct912 11:54 PM
boeing_737

0 
354 
in a battery, when all the electrons have transferred to the positive terminal ( i mean both terminals have same no....

Oct912 05:14 PM
Studiot

3 
736 
Hello!
I've been doing some excercises in mechanics and stopped for a moment over the thing that sometimes bothers...

Oct912 05:08 PM
mfb

1 
477 
I am studying the resistivity of various materials in my physics class and I have a query regarding conductive fluids....

Oct912 05:07 PM
Studiot

2 
451 
I have a question to depth understanding electricity
what's the thing that make electrical power appear???
I...

Oct912 04:19 PM
Naty1

5 
491 
Hi,
I'm trying to clear up a confusing point in the book by José and Saletan, concerning equivalent Lagrangians (in...

Oct912 12:49 PM
vanhees71

4 
801 
My book has introduced the idea of gauge invariance in terms of classical electrodynamics (attached file). However, I...

Oct912 12:38 PM
vanhees71

6 
1,059 
When we are sitting in our cars, and the car begins accelerating we are "pushed back" due to acceleration. Or if you...

Oct912 03:00 AM
Studiot

11 
1,085 
Consider the integral form of gauss's law
\oint \vec{E}.\vec{d \sigma}=\frac{q}{\epsilon_0}
Then lets write q in...

Oct912 02:15 AM
The_Duck

2 
769 
Does anyone know what the equations governing the effects of whistling in a convoluted tube as air passes trough it...

Oct812 10:58 PM
manjagu

2 
543 
Hi everyone! This is my first post here at PF after years of on & off lurking!
So, I'll get straight to it. At...

Oct812 11:52 AM
courtjester14

0 
362 
A boat is 4 m long and there is a person standing on one end of it. He walks across to the other end of the boat. The...

Oct812 08:44 AM
sidzekrom

2 
831 
I recently learned that ohms law is not always obeyed. I found this surprising because I thought ohms were defined in...

Oct812 08:28 AM
andrien

3 
1,148 
Everyone knows about the law of the lever, in order for a seesaw to balance the torques must cancel each other.
...

Oct812 06:46 AM
Vanadium 50

7 
1,007 
This may or may not be a crazy question but do centrifuges weigh more when they're spinning? Perhaps I'm...

Oct812 05:25 AM
Qreeus

2 
583 
In a massspring system that is driven by an external force, its displacementtime graph consists of several...

Oct812 02:26 AM
vanhees71

2 
502 
Hello everyone,
Does everything in the universe have potential energy? I know there are two main form's of energy...

Oct812 01:12 AM
Miyz

3 
806 
Just curious, does anyone know what are the equations for the displacementtime graph of a Keplerian orbit?
The...

Oct712 08:11 PM
holtto

2 
594 
physcially, how electrons choose the path with min resistance
if 2 paths of 2 differnet resistances
electrons...

Oct712 04:01 PM
klmnopq

9 
1,278 
Basically I have a question regarding the heat capacity of a gas and the ideal gas law.
The heat capacity equation...

Oct712 02:34 PM
randombill

15 
3,259 
Can anyone give me a simple proof of planck's radiation distribution law ?

Oct712 11:27 AM
Shan K

3 
696 
Hi everybody,
Can somebody help me with the following proof.
Show that for the Poincaré group
P=T\odot L
...

Oct712 11:26 AM
aoner

0 
655 
This has been bothering me for a while. Consider a varying magnetic flux through a closed loop. Faraday’s law says the...

Oct712 10:24 AM
John94N

5 
1,269 
I have a question: when the poynting vector and energy propagation in electromagnetic waves are in the same direction...

Oct712 07:22 AM
mfb

1 
653 
Hello,
I have temperature and emissivity data values for different land types (i.e. rock, vegetation etc.) of an...

Oct712 07:16 AM
Ardit

0 
538 
Hey all, I have a question that arose out of some thermodynamics review I'm going over for an upcoming course. It...

Oct712 06:56 AM
voko

1 
560 
In McCauley's book Classical Mchanics: Transformations, Flows, Integrable and Chaotic Dynamics we are analyzing a...

Oct712 02:34 AM
mjordan2nd

4 
623 
Cohesive forces holds stuff together, these forces being strongest in solids. However, why don't things (say, a stone)...

Oct612 09:39 PM
Nugatory

1 
723 
Hey, guys, my first time posting here but I need some educated individuals to definitively solve a problem from...

Oct612 05:27 PM
HXB

9 
1,381 
I've got a flywheel spinning at 850RPM. It weighs 112,34g and has a radius of 38mm.
I want to calculate the Kinetic...

Oct612 03:41 PM
CognitiveNet

8 
1,105 
See attachment
the green spot shows the initial position of a particle
the blue spot shows the position at which...

Oct612 11:34 AM
physicsfirzen

4 
485 
In Goldstein, the action is defined by I=\int L dt. However, when dealing with constraints that haven't been...

Oct612 02:54 AM
mjordan2nd

3 
752 
Hello,
I have the third edition of Goldstein which I have been using to learn mechanics. I believe I have found an...

Oct612 02:52 AM
mjordan2nd

3 
663 
First post here in PF, so forgive me if this question is in the wrong place.
I'm a student in computational plasma...

Oct512 09:41 PM
Muphrid

1 
556 
After studying some of the proofs of equations, worries arises about their uniqueness.
1.Removal of integral
∫∇．Edτ...

Oct512 08:22 AM
andrien

1 
483 
Does the line of a force applied need to go through the centre of mass to cause translational acceleration?
I have...

Oct512 07:45 AM
decerto

7 
732 
1What's the difference in Magenetic between B,H or in electric between D,E?
2what's permanent magnet and how it...

Oct512 07:01 AM
klmnopq

5 
779 