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visits member for 4 years, 2 months
seen 15 hours ago

16h
answered Does stopping the same bike and rider at the same velocity with the front brake require less energy than the back brake?
16h
comment Why do we ignore rotational energy in monatomic gases?
Once it contributes, you have three axes for rotation, so $\frac 32kT$ becomes $3kT$. This is the same for molecules larger than diatomic. For diatomic molecules near room temperature we ignore rotation around the long axis, so there are two instead of three degrees of freedom. The motivation is the same. The MOI is so small the DOF is not excited.
16h
comment Why do we ignore rotational energy in monatomic gases?
Then the MOI is decreased because now you have a bare proton. That means the temperature where the degree of freedom becomes important is higher-I suspect much higher for the reasons in my last comment. Other things may be going on by then-increasing number of electrons contributing the $\frac 32kT$ would be my first guess.
16h
comment Why do we ignore rotational energy in monatomic gases?
Aside from hydrogen, an ion has almost the same moment of inertia as an atom. I think (but didn't do the calculation) that the electron cloud has most of the MOI of an atom in the classical picture. The electrons are $2E3$ times less massive than the protons, but the radius (which gets squared) is $1E5$ times greater or more.
17h
answered Why do we ignore rotational energy in monatomic gases?
2d
comment Drag in low earth orbit
If you don't include gravity gradient, then there is nothing to prevent the arrow from flying straight. The damping comes from transverse drag. If the arrow is spinning, there will be drag to slow the rotation down. That may be in your step 4.
2d
answered Drag in low earth orbit
Jul
3
comment Radiation from home heaters
@CuriousOne: It is true you can get burned by a heater, but the wording convinces me that OP believes all radiation is harmful, not can be harmful.
Jul
3
comment Radiation from home heaters
This assumes all "radiation" is equally dangerous, which is clearly false. Different types of radiation (note that sound is included as well as electromagnetic) have different damage pathways and different danger levels. -1
Jul
3
answered Circle becomes Sphere in 3d?
Jun
27
answered Green light on red article
Jun
27
answered How do I incoporate gyro information in my position and velocity calculation?
Jun
26
comment Cylindrical capacitor in an electric circuit
If you think about having $R$ connected to the cable and then connecting the battery/$R0$, the capacitor starts completely discharged. As the capacitor cannot change voltage instantly, the current will flow through $C$. With a time constant of $RC$ the current will shift to the resistor. As $t \to \infty$ the current in $C$ will go to zero and you will have a constant current in $R$.
Jun
26
comment Cylindrical capacitor in an electric circuit
Yes, that is the capacitor. Once you calculate $E(r)$ you can use that to compute the capacitance of the coaxial fiber per unit length.
Jun
26
comment Unable to understand relative motion
You probably wouldn't see the same effect if everything outside the van is the same distance from your route of travel. I made a long drive yesterday with mountains in the distance on both sides of the road. It looked like the mountains were moving with us in the direction of travel with everything nearer to us than the mountains moving rapidly backwards.
Jun
26
comment Cylindrical capacitor in an electric circuit
As I reread it, I think you are correct that the wrapper is connected at both ends. Your circuit is correct as well. They say that at large time no current flows through the capacitor, which I misread as the wrapper. In your circuit, you have current flowing around the outside loop permanently in just the amount stated in the problem. Now C charges according to the voltage divider formed by the two resistors across the battery.
Jun
26
comment Cylindrical capacitor in an electric circuit
I had seen the picture as showing an external wire from $R_0$ to $R$. If the bottom line is the bottom edge of the wrapper and $R$ is connected from the wrapper to the center conductor, you have continuous current in the wrapper.
Jun
26
answered Cylindrical capacitor in an electric circuit
Jun
25
answered How can we see objects that are so far away?
Jun
25
answered Unable to understand relative motion