# All Questions

906 views

### How do EM waves propagate?

I have read about this and what I surmise is that when charged particles such as electrons accelerate they produce time-varying electric fields. These E-fields produce H-fields and the process goes ...
143 views

### How does enthalpy help us to find the state of equilibrium?

For an adiabatic system with constant external (generalized) forces, in a state out of equilibrium we have: $$\delta H\leq 0$$ If I understand correctly, derivation of this inequality does not rely ...
6 views

### What is a safe viewing distance for nuclear fireworks?

So people are setting off explosions and bragging about how big they are (fourth of july, you know), and I was wondering about setting off a big one. So lets say that the local firework show wanted to ...
2 views

### How does an inductor store magnetic energy?

So I am trying to figure out what the potential energy of an inductor with a current really means. In a capacitor, the energy stored works like this: if you let the plates attract each other, before ...
15 views

### Work done in a capacitor with a conductor between its plates

I have been agonizing over this problem, and have tried for more than two hours two find it with Kirchhoff equations, but I end up with 0=0 or some algebraic monstrosity. I have the following ...
72 views

### Speed as the fifth dimension

In spacetime there are four general dimensions, three of space and one of time. Why is it that other dimensioned qualities seem to be rarely considered as part of spacetime? For example, why isn't ...
48 views

### Why is the definition of mass and matter interlinked?

In my textbook the definition of matter and mass are: Matter: Any thing that occupies space and has mass . Mass: The amount of matter contained in a body. While defining "matter" we refer to ...
9 views

### Is the wobbly rope depiction of a radio wave inherently wrong? And how do vectors of parallel waves align with each other?

I don't have a scientific education, yet I'm scientifically curious. Among other things, I'm struggling to understand the nature of electromagnetic waves. What I have recently realized is that the ...
43 views

### How much force does it take to move the Earth?

If you could fly and survive in space, how much force would you need to move Earth at 1 meter per second?
371 views

### How does the heat death looks like from inside the system?

As this answer points out, any human would first freeze rather than experience the heat death. However, assuming hypothetically that we could make some robot live at such low temperature (or even ...
407 views

### Are there any non dissipative-non conservative forces?

Although the question stands for itself, I would like to know that if the answer has to be no then does any particular law forbids the existence of such forces; and if there are such forces then what ...
24 views

### Thermal contact burn

My client fell asleep in a bus stop leaning back against 3/16 in clear plate glass For an hour with a tee shirt on. It was about 80 degrees Fahrenheit and the sun was shinning on the glass. He woke up ...
44 views

27 views

### Wavelength of light too long to measure electron position in double-slit experiment?

I'm a mathematician, so I am not familiar with experimental physics. I am watching MIT course on Quantum Mechanics, and they describe the two-slit experiment with electrons passing through the slits. ...
103 views

### Projectile, air resistance and wind

So for my school project I am working on a projectile simulator and air resistance. So I have looked at this. Equations for an object moving linearly but with air resistance taken into account? ...
81 views

### Why is wave energy zero at maximum deviation?

The equation for the energy density of a longitudinal wave in a thin rod is $$w = \rho\cdot \left(\frac{\partial \xi}{\partial t}\right)^2$$ So the energy density seems to be 0 when the deviation ...
29 views

### How does a Venturi Injector comply with energy conservation?

How does a Venturi Injector comply with energy conservation? When the water flow enters the narrower cross section its velocity increases and its pressure decreases. When the pressure gets lower ...
720 views

### The uncertainty principle and black holes

What are the consequences of applying the uncertainty principle to black holes? Does the uncertainty principle need to be modified in the context of a black hole and if so what are the implications ...
204 views

### Atomic nearest neighbor notation

I recently got a correction to a paper that I am writing. The correction references a section in which I talk about nearest neighbors. The comment says: Do you mean NN, NNN, etc., or NN, 2NN, 3NN? ...
28 views

### What am I missing in this reasoning?

In studying the problem of locomotion at low Reynolds number, one possible approach is based on gauge theories. In simple terms, one considers a sequence of shapes of a certain deformable body, say ...
40 views

### Radiation from home heaters

My understanding of radiation is energy being emitted from a source. So much radiation would come out of a home gas or oil heater to become dangerous. I'm assuming infrared radiation.
863 views

### Can we know if “all” physical laws are discovered?

Before Einstein, scientists believed that all physical laws to be discovered were already discovered. Of course, that was proven wrong. If we somehow manage to come up with the Theory Of Everything ...
73 views

### The relation between mass and speed

Massless particles (or luxons) have no (rest) mass ($m = 0$) and a speed equal to the speed of light ($v = c$). Massive particles (or bradyons) have mass ($m > 0$) and a speed lower than the speed ...
77 views

### Conversion of energy to matter or antimatter?

We all know that matter converts into energy, but will energy convert into matter? Does it form antimatter by converting? Illustrate me with example.
143 views

### Origin of Universe

The universe is believed to have originated from absolutely nothing, and we know it is still expanding. Physics says "something can arise from nothing". I understand how mass and energy are related ...
165 views

### Is there any physically relevant example of constructing series solution about infinity of an ordinary differential equation?

I was reading about how to test if a given second order ordinary differential equation has singularity at infinity from Arfken and Weber. I understood the steps mathematically but I could not find its ...
So, I'm attempting a solution to the following problem: I am given a particle with spin 1/2 in a constant vertical magnetic field and a rotating field in the (x,y) plane. B(t) = [B_1\cos(\omega ...