Most Popular
1500 questions
77
votes
20 answers
Why doesn't current pass through a resistance if there is another path without resistance?
Why doesn't current pass through a resistance if there is another path without resistance? How does it know there is resistance on that path?
Some clarification:
I understand that some current will flow through the resistance.
A depiction of this…
ten1o
- 1,235
77
votes
7 answers
Number theory in Physics
As a Graduate Mathematics student, my interest lies in Number theory. I am curious to know if Number theory has any connections or applications to physics. I have never even heard of any applications of Number theory to physics. I have heard…
C.S.
- 1,029
77
votes
6 answers
Does gravity CAUSE the bending of spacetime, or IS gravity the bending of spacetime?
In reading these discussions I often see these two different definitions assumed. Yet they are very different. Which is correct: Does gravity CAUSE the bending of spacetime, or IS gravity the bending of spacetime? Or do we not know? Or is it…
foolishmuse
- 4,551
77
votes
1 answer
Does Feynman's derivation of Maxwell's equations have a physical interpretation?
There are so many times that something leaves you stumped. I was recently reading the paper "Feynman's derivation of Maxwell's equations and extra dimensions" and the derivation of the Maxwell's equations from just Newton's second law and the…
Yuzuriha Inori
- 1,897
77
votes
8 answers
Does a thrown ball have kinetic energy at the top of the curve?
I'm going through physics with my 5th grade child. There is a question and answer that indicates that a airborne ball at the top of the trajectory does not have kinetic energy.
The diagram below shows the path taken by a ball after it was kicked.…
meow
- 967
- 1
- 6
- 7
77
votes
3 answers
Why does my beveled mirror make triplicate "ghosts"?
Here is a picture of my power adapter. You can see in has one green LED lit when charging.
Now here is a picture of my mirror with beveled edges. When I view the power adapter in the mirror, I see three (3) projections of the LED: the original,…
istrasci
- 1,013
77
votes
20 answers
Is weight a scalar or a vector?
My professor insists that weight is a scalar. I sent him an email explaining why it's a vector, I even sent him a source from NASA clearly labeling weight as a vector. Every other source also identifies weight as a vector.
I said that weight is a…
Ryan
- 787
77
votes
3 answers
Is there 'friction' in spacetime?
So, if all the bodies are embedded in space-time and moves through it, is there some kind of 'friction' with space time of the planets? For example, the Earth suffers friction when moving near the sun due the curvature and General Relativity and…
Jose Javier Garcia
- 4,719
77
votes
4 answers
What is this shadow being cast upon?
The picture below is from on top of Mt. Shasta at sunrise. The sun was directly behind me when I took the picture and it appears to be casting a shadow on.... the sky itself?
Can anyone explain what the shadow is being cast on? There don't…
Abe Miessler
- 865
77
votes
9 answers
If the speed of light is constant, why can't it escape a black hole?
When speed is the path traveled in a given time and the path is constant, as it is for $c$, why can't light escape a black hole?
It may take a long time to happen but shouldn't there be some light escaping every so often?
I'm guessing that because…
Zaibis
- 1,289
- 1
- 11
- 19
77
votes
3 answers
Why doesn't the motion of a car affect the frequency of radio stations?
When we go in a car and tune to an FM radio station, why doesn't our motion disturb the frequency?
Like the Doppler effect?
DARU SRINIVAS
- 843
76
votes
7 answers
What is the difference between Newtonian and Lagrangian mechanics in a nutshell?
What is Lagrangian mechanics, and what's the difference compared to Newtonian mechanics? I'm a mathematician/computer scientist, not a physicist, so I'm kind of looking for something like the explanation of the Lagrangian formulation of mechanics…
grautur
- 941
- 1
- 8
- 6
76
votes
8 answers
If I stood next to a piece of metal heated to a million degrees, but in a perfect vacuum, would I feel hot?
A friend of mine told me that if you were to stand beside plate of metal that is millions of degrees hot, inside a 100% vacuum, you would not feel its heat. Is this true? I understand the reasoning that there is no air, thus no convection, and…
Peter_Browning
- 919
76
votes
5 answers
How does an ordinary object become radioactive?
In the 2019 miniseries "Chernobyl", ordinary objects are depicted as being capable of becoming radioactive, such as clothes, water, stones.
How exactly does something composed of a non-radioactive mass, become radioactive?
I'm aware of the…
AlphaCentauri
- 829
76
votes
5 answers
Is fire plasma?
Is Fire a Plasma?
If not, what is it then?
If yes why, don't we teach kids this basic example?
UPDATE: I probably meant a regular commonplace fire of the usual temperature. That should simplify the answer.
daniel.sedlacek
- 1,925