swansont

There's not an absolute cutoff, though, so the choice is somewhat arbitrary for saying what the visible range is. The eye efficiency looks sorta gaussian, but a lot of the time a linear scale is shown, rather than a log scale, which makes it look like the efficiency goes to zero at 400nm and 700nm. I've used lasers at 780 nm and could see diffuse reflections at low power (a few mW). I've also seen 852 nm light (a few hundred mW source) which made me realize that I wasn't wearing my laser goggles.

The drag depends only on the speed of the object. If you increase your thrust, your speed will increase but then so will the drag, until you reach the speed where they are equal. Then the net force will be zero, and speed will be constant.

This is called anomalous dispersion. No violations of causality occurred.

Evolution doesn't have to be gradual to that extent. A mutation that proves to be beneficial will tend to spread through a population and this will take time, but not necessarily millions of years. (Keep in mind that it's really the number of generations that matter, and many organisms have shorter life cycle times than humans do.)

I think any of the noble gases will act like ideal gases, since they don't form molecules. Others will too, to varying degrees.

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.