5,807 reputation
1915
bio website none
location somewhere on earth
age 60
visits member for 4 years, 3 months
seen 23 hours ago

Jul
27
answered Do matter and antimatter annihilate or release energy?
Jul
25
answered What happens to a radioactive element or isotope's electrons when it undergoes alpha decay?
Jul
25
comment How can the orbit of Jupiter's moons be used to calculate the speed of light?
@Javier: No. We are not looking at the time between eclipses, we are looking at the absolute time of each eclipse. If the distance from Earth to Jupiter did not change the times would be a nice arithmetic progression. The motion of Earth imposes a sine wave on the time with amplitude the light time over the diameter of the Earth's orbit around the sun (assuming Jupiter's orbit is circular). We asses the effect and find the light travel time over the diameter of Earth's orbit.
Jul
23
comment What is the work done?
@JohnM: I believe showing the calculation of the PE change in the barrel is enough to satisfy this. OP has isolated the question to which value is being asked for.
Jul
23
answered Why did the matter in the early universe not stick together due to gravity?
Jul
23
answered What is the work done?
Jul
23
answered If you compress air to a large enough pressure do new molecules form that have a large activation energy?
Jul
19
revised Why must the particles of an ideal gas be point-like?
correct typo
Jul
18
answered Would the terminal velocity of a roller coaster train differ on the track from if it was free falling through air?
Jul
8
comment Tritium decay is spontaneous even if the binding energy of tritium is higher than the binding energy of 3He. Why?
This is spot on. The point is that the masses of the atoms include the electrons, so the decay is favorable from an energy standpoint.
Jul
6
answered Does stopping the same bike and rider at the same velocity with the front brake require less energy than the back brake?
Jul
6
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.
Jul
6
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.
Jul
6
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.
Jul
6
answered Why do we ignore rotational energy in monatomic gases?
Jul
3
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.
Jul
3
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?