# All Questions

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### Black-holes, space time and their bending

I have been watching some videos related to how space-time is bent because of the mass (just "visually", not mathematically), and then I watched some videos about black holes. My own conclusions ...
15 views

### Order of magnitude!

I'm having a hard time determining the order of magnitude for these quantities: Heartbeat: $93\,{\rm bpm}$ Mass: $93\,{\rm kg}$ Height: $1.75\,{\rm m}$
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### Converting the derivative into a particular form

I have found the derivative which is $$dy/dx = \frac{-2x(X+1)}{(X+2)^5}$$ however how would you express this derivative into the above form.
31 views

### is it possible to get “100% sure” physical/chemical measurements and/or “100% clear” compounds? [on hold]

The obvious question for any serious movie fan of the famed "Breaking Bad" series is, arguably, "is the chemistry setting (e.g. the famous "Heisenberg Purity") realistic at all?". The question itself ...
4 views

### Why does a system have to be holonomic?

So I'm doing some work from Taylor's mechanics book. He says for the problems in the book, we require the system is holonomic - that is the number generalized coordinates = number of Deg. of freedom. ...
25 views

### Rockets and distance

I am trying to create an equation which allows for me to change the aspects of the rocket so i can calculate the distance traveled vertically. My idea is for a rocket that only moves vertically; ...
3 views

### Relativity and Projective Geometry

How do you identify the cross ratio equation of projective geometry from the hyperbolic geometry of relativity? Specifically, what relativistic variables would correspond to A,B,C,D in the standard ...
3 views

### Path length difference from multiple sources?

I know that path length difference is given by the difference in the distance from each source to the observer, but I feel like this doesn't apply when some of the distances are the same, like in the ...
17 views

### Why is there a universal speed limit

I am looking for an answer that does not rely on Special or General Relativity -and without recourse to the fact that the speed of light is frame invariant. Is there another way of showing this ...
15 views

### if potential function is given for free space , how to find total charge on a conductor placed there?

Consider the following potential function in free space: $$V = \frac{100xz}{(x^2 + 4)}$$ If the $z = 0$ surface is a perfect conductor then find the total charge on that portion of the conductor ...
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### How to determine the observables rigorously?

In Quantum Mechanics, as I know, if a system is described by a Hilbert space $\mathcal{H}$, each physical quantity is associated with some hermitian operator $A : U\subset \mathcal{H}\to \mathcal{H}$ ...
195 views

### Difference between directional and omnidirectional transmission or reception?

It is suggested that the next generation wireless technology will be highly directional since this increases the signal gain (MIMO) and decreases interference. How will the receiver still be able to ...
39 views

### Does charge conjugation affect parity?

Notice that these transformations do not alter the chirality of particles. A left-handed neutrino would be taken by charge conjugation into a left-handed antineutrino, which does not interact in ...
374 views

### What is the meaning of spin two?

As the title suggests, what is the meaning of spin two? I kind of understand spin half for electrons. I can kind of understand spin one for other particles. However I'm not sure how something could ...
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### Is the cosmic microwave background radiation red shifted?

My question is. If the cosmic background radiation is red shifted how would you calculate the wavelength at the time it was emitted ?
115 views

### Kinematics of Euler angles relative to a rotating frame

I have a rotating body $B$ and a rotating frame $F$ whose orientations are described by the quaternions $q_B$ and $q_F$ respectively. I also have the angular velocity vectors $\omega_B$ and ...
104 views

### Forces Create Angular Acceleration And “Straight” Acceleration - But How Much Of Each?

Let me set up the following problem for a rectangle floating in space: We know its dimensions. We know its mass. There's a force pushing it for a known amount of time - we know the angle & ...
Suppose we have a theory is covariant under the Spin group Spin(2n-1; 1). We consider the real vector space $V = R^{2n-1,1}$, which naturally comes with a Lorentzian inner product. On this vector ...