Linked Questions

1
vote
2answers
65 views

A battery generates current according to the resistances within a circuit(V=IR)

A battery generates current according to the resistances within a circuit(V=IR).The charged particles enter and exit the source with the same magnitude, however, since we have said that the current is ...
24
votes
6answers
4k views

Speed of electrons in a current-carrying metallic wire: does it even make sense?

Does it make sense to speak about the speed of electrons in a current-carrying wire (non perfect conductor)? If so, what is their speed? Here are my thoughts: On the Internet (Wikipedia, ...
0
votes
3answers
111 views

Velocity of a falling body as a function of time AND mass [duplicate]

I'm working on a small java program, and I was wondering if there was an equation to calculate the approximate velocity of a falling body, in function to its mass $M$ and the time $t$ since the ...
32
votes
8answers
15k views

Since cables carry electricity moving at the speed of light, why aren't computer networks much faster?

Why can't cables used for computer networking transfer data really fast, say at the speed of light? I ask this because electricity travels at the speed of light. Take Ethernet cables for example, I ...
3
votes
4answers
7k views

What experiments prove the greenhouse effect?

What experiments prove that heat can be "trapped" by a layer of material with suitable optical properties, such as carbon dioxide? I've read a little on Wikipedia but I've got only some names, not the ...
5
votes
5answers
1k views

This sentence makes no sense, electrostatics and electrons moving in a conductor - current

I highlighted the part where the confusion is. The sentence said that the potential difference is 0, yet it then immediately talks about how electrons can have motion. What are they trying to say?
12
votes
9answers
2k views

What objective criteria distinguish between valid science, fringe science and pseudoscience in physics?

Plenty of research activity in physics have been vigorously opposed by their opponents as pseudoscience or fringe science, while other research are mainstream. It is possible some topic is ...
2
votes
0answers
253 views

false false beliefs in physics [closed]

Reading Common false beliefs in Physics I feel that there are also "fake false beliefs", ie, that the "false belief" does not actually exists, it is a rhetorical argument or just a basis for ...
4
votes
1answer
213 views

What near-future measurement technique improvements will extend our physical knowledge?

Inspired by the wiki-article on atom-lasers: Another application, which might also benefit from atom lasers, is atom interferometry. In an atom interferometer an atomic wave packet is ...
0
votes
1answer
893 views

Famous physicists' quotations [closed]

I recently watched Sydney Coleman's 'Quantum Mechanics In Your Face,' and very much enjoyed it. (Highly recommended.) In it, Professor Coleman quotes a very clever comment by a philosopher called ...
21
votes
7answers
48k views

How efficient is an electric heater?

How efficient is an electric heater? My guess: greater than 95%. Possibly even 99%. I say this because most energy is converted into heat; some is converted into light and kinetic energy, and ...
2
votes
2answers
2k views

Appearance of atoms

I was watching a documentary entitled "The Atom" and one of the statements made was that Atoms behave differently when we look at them. I wasn't too sure about the reasoning behind this and i'm hoping ...
23
votes
3answers
9k views

Is kinetic energy a relative quantity? Will it make inconsistent equations when applying it to the conservation of energy equations? [duplicate]

If the velocity is a relative quantity, will it make inconsistent equations when applying it to the conservation of energy equations? For example: In the train moving at $V$ relative to ground, ...
238
votes
16answers
61k views

Why does kinetic energy increase quadratically, not linearly, with speed?

As Wikipedia says: [...] the kinetic energy of a non-rotating object of mass $m$ traveling at a speed $v$ is $\frac{1}{2}mv^2$. Why does this not increase linearly with speed? Why does it take so ...