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

Apr2211 05:26 AM
ZapperZ

1 
45,902 
I have an image taken with a camera. I know the f/#, focal length, CCD characteristics, and an approximate distance to...

Aug3012 08:54 AM
Andy Resnick

10 
1,319 
Here is a simple example about my issue with this. 1g ball (ball A) moving west at 10m/s hits another 1g ball (ball...

Aug3012 07:49 AM
mickybob

6 
3,252 
Here is a quote from one of the MIT notes on magnetism :
"Note that F(magnetic force) is perpendicular to v and B ,...

Aug2912 05:57 PM
gabbagabbahey

9 
1,073 
I have a question. All things being equal as far as flow and pressure goes...where would the gas preferentially flow...

Aug2912 04:08 PM
Integral

14 
913 
Hey I just wanted to check with y'all, but I feel I'm fairly well acquainted with momentum and the rules surrounding...

Aug2912 02:53 PM
A.T.

1 
1,013 
Hi everyone I have a quick question regarding heat transfer. I have yet to study heat transfer yet but I have a basic...

Aug2912 01:56 PM
pa5tabear

1 
594 
I need to calculate the torque needed to move an object in horizontal direction. The object is subjected to a force P...

Aug2912 07:34 AM
mfb

1 
862 
I am not sure if this is wright section for this question,so please excuse me if a made a mistake.
I am thinking of...

Aug2912 02:27 AM
Bobbywhy

4 
654 
The cartesian sign convention for a convex lens is follows:
1. All distances on the principal axis are measured from...

Aug2912 02:24 AM
Simon Bridge

3 
541 
Hey,
I am helping out with a class and the students were given a question about an electroscope that is being...

Aug2912 02:22 AM
Simon Bridge

3 
993 
Hi
I had a few thermodynamics questions on a thread that was locked. The link is here and my questions are directed...

Aug2912 02:13 AM
Darwin123

20 
2,378 
I am trying to better understand some concepts in magnetism and I hope that someone here can help clarify a few...

Aug2912 01:17 AM
SamBam77

3 
865 
Suppose a permanent barmagnet is placed inside a toroid/torus and the toroid is then completed and power applied. How...

Aug2812 11:09 PM
Simon Bridge

3 
1,379 
Hello Forum,
In kinematics we study motion and the trajectories of moving bodies.
The trajectory is a line...

Aug2812 01:56 PM
voko

4 
1,042 
How exactly does water behave in a magnetic field? I've seen pictures of a boat that uses electromagnetic rail...

Aug2812 01:11 PM
soothsayer

5 
847 
I'm interested in working out an efficient and precise numerical method to find the charge density on a conductor with...

Aug2812 11:33 AM
bcrowell

5 
993 
Say an object is dropped out of a plane at height h above the ground and flying at a constant speed v0...
Ignoring...

Aug2812 09:10 AM
mfb

2 
680 
Hi all!
I'm trying to study the Poincare group and I have one problem. I'm reading a book: Gross D. Lectures on...

Aug2812 12:43 AM
vanhees71

2 
904 
Hi
My textbook mentions
"We know that in an electrostatic situation (with all charges at rest) the electric...

Aug2712 09:25 PM
gabbagabbahey

1 
861 
what creates magnetic fields, magnetic poles or currents? are those theories equivalent mathematically? i read in...

Aug2712 08:28 PM
BruceW

1 
516 
Thermoelectrics convert heat to electric power (albeit a meager amount), It reduces the entropy of a system.
Does...

Aug2712 06:51 PM
Darwin123

14 
1,208 
Hello everybody, I would like your comments on my findings and perhaps prompt me to look at relevant literature.
...

Aug2712 05:16 PM
soothsayer

6 
662 
In a collision the colliding particles will in general have different velocities at different instants of time....

Aug2712 04:48 PM
voko

9 
944 
Suppose you push a stick by a distance of s like on the picture. It will start to rotate as you along. My question is:...

Aug2712 02:37 PM
aaaa202

2 
614 
Hi,
I'm Chaitanya, 4th year undergraduate student in biomedical engg.
I have an idea of making a mobile phone...

Aug2712 01:04 PM
Kaycee92

2 
631 
I have been out of school a long time, so please go easy on me. If the answer is an equation with symbols or letters,...

Aug2712 09:28 AM
cowpup

2 
975 
I'm looking at the free energy of a body (theory of elasticity) but I can't really square the general expression with...

Aug2712 08:28 AM
malasti

4 
773 
This doubt is nagging in my mind for couple of days,and its makes the rest of the things so dizzy and confusing.Heres...

Aug2712 07:22 AM
Redbelly98

11 
1,422 
Hypothetically, if I had a sphere and a block (of the same mass and material (hence the same coefficients of static...

Aug2712 07:20 AM
Maertens

11 
3,014 
Someone asked me how Faraday's Law of Induction and Ampere's Force Law, both which form part of Maxwell's Equations,...

Aug2712 06:52 AM
Lamarr

4 
3,228 
Can anyone tell me the physical interpretation of the flux of an electric field through a closed surface. I think I do...

Aug2712 03:15 AM
luitzen

6 
1,590 
I have a thought experiment for physicists and thermodynamicists and the like. Those who are always looking for 2+2=4...

Aug2712 12:09 AM
K^2

13 
1,551 
Hi all,
I'm doing what should be a pretty simple problem, but some theory is giving me trouble.
Basically, in...

Aug2612 10:20 PM
gabbagabbahey

1 
946 
Quote: "All moving charged particles produce magnetic fields."
Hypothetically  if you took a bunch of charged...

Aug2612 01:10 PM
StephenofCaly

4 
1,640 
Hi
In my book (Griffith's) there are two different expressions for the induced polarization, namely
P =...

Aug2612 09:24 AM
Niles

0 
595 
I have been wondering about the physical reason why a TE wave that goes STRAIGHT through the waveguide(without any...

Aug2512 06:33 PM
marcusl

4 
860 
http://www.physicsforums.com/showthread.php?t=27021
I saw this problem and I think that is interesting but that...

Aug2512 12:34 PM
matematikuvol

0 
477 
We have a metal sphere of radius R in the space and resistivity p. At a distance d>R from it we have antoher sphere of...

Aug2512 06:49 AM
Salah93

0 
512 
I want to get some terminology straight.
A nonautonomous system is as far as I can understand a system, where the...

Aug2512 06:06 AM
voko

1 
938 
Calculating the internal energy of gasoline is fairly simple, because it wouldn't vary much with temperature or...

Aug2412 07:30 PM
Drakkith

1 
718 