swansont

A ml is a cm3

The drag equation uses v2 because the force depends on the square of the speed. If you go twice as fast, the drag is 4 times bigger. That's what has been observed to hold. You don't use v because it doesn't depend linearly on v. There is probably a theory that shows why the term is v2, but if anyone here knew it they'd probably have posted it by now. If I had to guess, I'd say that it's a combination of imparting momentum to air molecules by collision, which depends on the relative speed, and trying to compress/do work on the air (or whatever fluid) which would also depend on the relative speed. So you end up with a combination of the two effects, which is nonlinear and thus depends on v2. Again, this is a guess.

Interesting in what way?

It's an astrological "effect," not an astronomical one, associated with Mercury going retrograde. That is, Mercury's path appears to change direction, because of its different orbital speed with respect to ours. Apparently astrologers associate Mercury with communication. There's nothing real to this.

This is certainly an extreme example that demonstrates your point, but even if the bullet were launched at below terminal speed, it would come down slower due to air resistance. Some of the original KE is lost to the air on the way up, and then even more is lost on the way down, so KEground, initial>PEzenith>KEground, final The final speed has to be smaller than the launch speed, assuming no change in mass.

That was part of my concern. I don't have the ability to nudge someone either way - it would be a shove. But it should be more than just disagreeing. I'm not about to ding somebody for having a different opinion or for an argument about semantics. It's going to have to be for bad science. And it's two dots at the moment. Somebody didn't like one of my answers.

That's a rather egregious abuse of significant digits you've got there.

It would be nice if you could vary the weight of feedback you give. Some posts are good but not great, and some are bad but not terrible. But if the system assigns the same point value for any recommendation (from a given user), you can't make that distinction.

1. This sounds a bit like Zeno's paradox. (aka Xeno, and there are actually several paradoxes) 2. Space and time are thought to be quantized, or at least current theories can't deal with them at some small scale. These are the Planck length (~1.6 x 10-35 m) and the Planck time (~10-43 s).

Note that solid-on-solid tends to have a lot of small air gaps, which end up being good insulators. You need to add some thermal grease or thermal epoxy (a thin layer) to get cood conduction.

If they are travelling waves, yes. But in a container, they can form standing waves which means there will be nodes, where the energy is a minimum. The rotating plate is there so the food doesn't stay in the nodeand helps even out the cooking. So it would be harder for the ant to stay inor near a node, but not impossible.

Newton's third law states that every force has a reaction. That is, FA-B = FB-A. A exerts the same force on B that B exerts on A. But thrust and drag are both exerted on the plane - the same object. The reaction force to either has to be a force that the plane exerts on the air.

Drag isn't the reaction force to the thrust. Thrust action/reaction is the force the propeller exerts on the air passing through it, and the force the air exerts on the propeller. Drag action/reaction is the force the plane exerts on the air by moving through it, and the force the air exerts on the whole plane. You can have thrust with no drag (e.g. plane bolted down with the prop running) and drag with no thrust (e.g. a glider).

Perhaps you've noticed that microwaving gives you hot spots and cold spots - that's due to constructive and destructive interference of the microwaves. That's why some more expensive ovens have a turntable or "stirrer" - it minimizes the extrema. I'm guessing you don't have one of these. When you microwave for several minutes, some of the cold spots may warm up by conduction with adjacent food, but it's still a null of microwave energy. So the ant probably just found a cold spot and camped out there. Ants can be small compared to the wavelength - 2.4 GHz is a little over 10 cm. Neither your food nor the ant became radioactive - there's an important distinction between that and being irradiated. Microwaves don't ionize, so heating is the main effect. Most legitimate concerns of microwaving (e.g. loss of nutrition) stem from local overheating and the chemistry that happens when food gets really hot; the fact that microwaves cause the heating is incidental.

Air resistance and friction are macroscopic phemomena. Atoms are mostly empty space, and a photon has the ability to pass through without interacting. If the photon does interact, it will either be absorbed or it will scatter. No more photon for the former, different energy photon, but travelling at the same speed, for the latter.

Well, not quite. There are radiactive isotopes of lead, and I think some decay chains go through these. But they beta decay to Bismuth and then to Polonium before alpha decaying to a different isotope of lead. Eventually it ends up as a stable isotope of lead.