# Search results

1. ### A Equipartition of energy in the modes of a resonant cavity

The equipartition of energy is seen in a system at thermal equilibrium. This is the necessary condition and is assumed for a black body cavity.
2. ### B How can a reaction force do work on someone who is jumping?

The change in kinetic energy of a system can be produced by the work of internal forces too. Review the work-energy theorem for a system of bodies with internal forces. It's the momentum that cannot be changed by internal forces but not so for KE.
3. ### B What is the meaning of the word "resolved"?

This is the meaning associated with the word "resolution". As in the resolution of a microscope or other instrument.
4. ### Draw the F.B.D. (Free Body diagram) of two blocks

Your FBD is almost correct. Just that F is horizontal and not vertical. The force acting vertically on the the small body is the tension in the string. As the pulley is rigidly connected to body 2, F acts horizontally on body 2. This is where is supposed to be in the FBD, if you split the...
5. ### Draw the F.B.D. (Free Body diagram) of two blocks

You don't need to analyse the bodies separately to answer the question. Just consider the system and the horizontal external forces. The body 2 had no vertical acceleration.
6. ### B Will graphene becomes a wonder material for future inventions?

It may be that you misread the forum title as "psychic forums"? :smile:
7. ### I Possible Error in Goldstein's Classical Mechanics 3rd Edition

Thank you. Google did not suggest it when I was looking for vasconomic. :) It does not know everything. Yet.
8. ### I Possible Error in Goldstein's Classical Mechanics 3rd Edition

What is the meaning of "vasconomic"? Google did not give any hit for vasconomic dynamics.
9. ### A Does electron energy contribute to current

I think you are confusing thermal phenomena with electrical conduction. Only electrons withing a few $k_B T$ contribute to the electron heat capacity. There is no such a requirement for electrical conduction. After all the expression for electrical conductivity contains the total free...
10. ### B Is there any physical quantity having two different units?

If they had different formulas, different units and apply to different conditions, by what logic would you even call them "the same quantity"?
11. ### Using acceleration to find tension (concept problem)

The tension acts on both objects not just on one of them. It is an internal force if you consider the system of the two objects.
12. ### B Basic Algebra Question: 3x = 15

It's a good option when you are familiar with the algebra. May not be so good when someone struggles to understand the general procedure.
13. ### B Is relativity universal?

Even your assumption that "temperature is relative" needs some explanation. Maybe you can explain what do you think "relative temperature" means. The sensations of cold and hot are "relative" in the sense that what one person calls cold may be hot for another or what we call warm weather in...
14. ### B Is relativity universal?

You may have the wrong idea about what theory of relativity is. Your example with temperatures does not have any relation to the purpose of the theory of relativity. It is not even an example of a "relative" quantity in the common sense of the therm.
15. ### B Basic Algebra Question: 3x = 15

Why do you need to factor 15? What if it si 3x=16?
16. ### Electrostatic potential of a circular ring

So when you say "you" you mean a generic person (who did not graduate) and not the OP. :) It looked like you were answering the question the OP asked in April 2014, right above your answer.
17. ### I Two or three types of heat transfer?

Electromagnetic interaction is not equivalent to "radiation". The atoms in a solid transfer thermal energy without emitting any electromagnetic radiation.
18. ### Electrostatic potential of a circular ring

The last post was from 2014.
19. ### B Confusion in explaining Kepler's second law in terms of energy

Kepler's second law is a consequence of conservation of angular momentum. Conservation of energy cannot "explain" it.
20. ### I Magnetic field "lines" confused with magnetic field "vectors"

Yes, the arrow at the south pole is in the wrong direction. The arrows on the lines simply show the direction of a magnetic field vector tangent to the line for any point on the line.
21. ### I Magnetic field "lines" confused with magnetic field "vectors"

The magnetic field vector at the south pole is drawn the wrong way. It should enter the magnet.
22. ### B Question about conservation of angular momentum for charges

Well, if the small charge has no initial velocity it will move along a radial direction and the angular momentum will be zero in any position. The angle alpha in your formula is zero. If it has some non-radial component it will have some angular momentum (in respect to the fixed charge). But...
23. ### B Question about conservation of angular momentum for charges

What is the trajectory of you particle?
24. ### I Question about the moment/torque principle

What you should ask about is the force on the fulcrum rather than "weight at the fulcrum" (which is meaningless, as already pointed). The force on the fulcrum may be equal to the weight of some objects but not necessarily. If you replace one of the object with the force applied by a hand holding...
25. ### B How to use Lenz' law

Is that rectangle moving down a loop or just "a conductor", as described in the OP?
26. ### I Textbook says V=E/w but units don't match

What book? What page? Can you post a scan of the page?
27. ### I Typo in elliptical orbit energy derivation?

It would depend on what is the angle. Or where. It says it is the polar angle, right?
28. ### I Isn't planetary rock dating really supernova dating?

Some of the atoms came from supernova. But not the compounds in the Earth's rocks. The dating method determine the age of the rocks and not the age of the atoms. If you could determine the age of the heavy atoms you could tell how long ago they were formed in a supernova. This would be...
29. ### B Depth effect in mirror reflections

Regarding the example of the blue object, you This may be one source of your confusion. An object that we call blue usually reflects all visible wavelengths, more or less. If you shine white light on it and look at the spectrum of reflected light you may see an increased reflectivity over some...
30. ### I When a mass is in SHM, what is the relationship between velocity and acceleration?

The velocity (actually the speed or the magnitude of velocity) decreases when the acceleration is negative. Nothing to do with the fact that the acceleration is increasing or decreasing. It could be constant negative acceleration and the velocity will decrease too. The relation between...