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

Apr2211 05:26 AM
ZapperZ

1 
47,870 
Well, we all know that the farther you move the point of force application from the point of rotation, the greater the...

Jul708 12:40 PM
teodorakis

19 
13,619 
Is it possible to show that the maximum efficiency for a heat engine is given by
\eta = 1  \frac{T_c}{T_h}
where...

Mar2411 05:47 AM
netheril96

4 
13,606 
Hi,
I'm wondering what the difference between a light dependent resistor and a phototransistor is. Am i correct in...

Oct2106 05:47 AM
Reshma

2 
13,597 
is an emf produced by a changing magnetic field or by a moving magnetic field?

Nov2008 01:23 AM
Robin07

31 
13,581 
Hello all,
Just wondering if someone can give me a brief explanation of Wood's anomaly with regards to optics.
...

Mar2211 07:16 PM
astrosona

2 
13,575 
hello, I'm new here =D
dunno if this is the right section to ask this
I'm really confused about power voltage and...

Aug308 12:24 PM
russ_watters

4 
13,574 
Hello!
First post here :) Hope this isn't too simple for this forum...if so, by all means give me a pointer...
...

Oct410 01:42 PM
Zeppos10

26 
13,571 
Hi..
I have a question about AC magnetic field, wondering if you can help me understand this.
For a DC solenoid...

Jun1109 12:00 PM
Bob S

11 
13,566 
Since running a current through a wire will increase the temperature of the wire, is there an equation for calculating...

Dec2309 12:34 PM
Jake110

14 
13,562 
I've been having problems trying to come up with an answer for this seemingly simple question. I would think that...

Apr2205 02:32 AM
adiputra

11 
13,521 
As far as I know, you can't prove laws, but anyway...
We got to do an experiment at school. A weight is suspended...

Jan1612 05:29 AM
harrylin

35 
13,513 
I'm studying for the Physics GRE and going over my thermo notes.
Ok, so for enthalpy change
(delta)H = (delta) U...

Oct1409 08:21 AM
Mapes

5 
13,504 
I was told by my teacher that the definition for distance is just "the amount of ground covered", and that...

Feb1509 11:33 AM
KellyOsbourne

4 
13,503 
I tried posting a similar question before, however, I've found the 1 reply is actually wrong. Hopefully with better...

Jan2408 08:16 AM
Andy Resnick

2 
13,484 
I am trying to find out how fast a vertical cylindrical water column heats due to the ambient temperature. I already...

Jun710 07:48 AM
Rimidalv

6 
13,466 
I was tutoring a student in an optics lesson the other day. We discussed the foundational concept, that light travels...

May2713 12:46 AM
Rajashik

41 
13,421 
There is no net gravity in a hollow sphere. You can get this result using calculus but that's not really...

Oct109 01:30 PM
stone1

29 
13,413 
Hi everyone,
I am no expert in any means, so if what I am asking is silly, just tell me.
This is an example. ...

Dec1912 11:57 PM
Chestermiller

16 
13,347 
Hi,
I've always tken for granted that KE=(mv^2)/2, but never seen the derivation! I think it probably comes from U=...

Feb1806 06:29 AM
Doc Al

1 
13,335 
Is the parallel axis theorem always valid for inertia tensors? We have only seen examples with flat (2d) objects and...

Dec108 08:19 PM
adriank

6 
13,322 
They say that vector laplacian is defined as the following:
\nabla^2 \vec{A} = \nabla(\nabla\cdot\vec{A}) ...

Dec208 03:54 PM
bcorso1

12 
13,320 
When a voltmeter measures the AC voltage in a circuit, does it measures the rootmeansquare value of the voltage? Is...

Oct1407 03:34 PM
mourici

14 
13,284 
Why is it that the equation for work done to stretch a spring is
W = 1/2k(x22x12)
while the work done by a...

Sep2009 08:26 PM
woodie37

11 
13,265 
I jump off a high bench (5ft high) to the ground. What is the gforce of the impact and how do you calculate it. It...

Apr1209 03:58 PM
joec_49

7 
13,254 
Hey Guys,
I know that this has been posted before, but mine is slightly different.
Our instructor only provides:...

Dec1907 08:16 PM
pervect

6 
13,242 
I've got an investigation in which iam investigating the factors affecting the perioad of a BIfilar pendulum. So has...

May605 12:57 AM
Graham

12 
13,231 
Conservation of linear momentum is consequence of which one of Newton's three laws?

Feb2309 11:10 PM
vjraghavan

9 
13,223 
I know the basic answer, that the movement of air sets things vibrating which makes noise, but I don't know the...

Apr2706 03:34 PM
miket

3 
13,212 
The air temperature at an altitude of 10,000 meters is a chilling
35º C. Cabin temperatures in airplanes flying at...

Feb2204 05:22 PM
russ_watters

5 
13,194 
I have been doing mechanics in college and in the present chapter,two of the concepts that I found rather confusing...

Mar2511 02:51 PM
tinytim

18 
13,181 
Hi,
1) Can anyone explain to me from a conceptual standpoint, why increased current leads to an increased voltage...

Sep910 07:49 AM
ZapperZ

23 
13,170 
Does the metal pole of most umbrellas increase significantly the risk of the bearer being struck by lightning? In...

Oct2810 01:51 PM
Bob S

9 
13,152 
So what is it?
This is not a homework question. But I anticipate a good discussion.

Jan2304 05:50 PM
ketch

23 
13,092 
Electricity (the flow of current) is said to travel at near the speed of light (7590%), but I read that electrons...

Oct209 12:54 PM
antd

38 
13,020 
May be this question has been asked multiple times here i was just unable to search it by topic or search term.
The...

Oct2312 02:31 PM
Naty1

14 
13,011 
hey guys just a quick question
Does anyone know the u value of jusy normal glass?
Ive looked everywhere and ive got...

May909 08:30 AM
russ_watters

3 
12,963 
What is the difference between "uniform plane waves" and "planes waves." Are these terms used interchangeably?
What...

May107 08:21 PM
Claude Bile

16 
12,958 
Why is the triple point of water .01C while the freezing point 0C? It seems contradictory.

Oct2407 12:26 AM
animalcroc

7 
12,953 
hey guys, i've been experimenting with a pendulum and while doing the error discussion for my experiments i got stuck...

Apr2809 08:46 PM
Volcano

8 
12,950 
I've been working on a simulation of a Lorenz Waterwheel, and friction was killing it  I couldn't use realistic...

Oct3111 03:47 PM
berkeman

14 
12,902 