swansont

Two things: 1. The minor issues here illustrate that there are assumptions being made. One might wonder why we would bother bringing them up. But since there is an obvious misconception at play, it's not clear at the outset whether the assumptions are involved. Sometimes the assumptions won't be valid. You have to check. 2. The main misconception here is one of not understanding perspective and how vision works in this regard. I would say it's far less mysterious than it's being portrayed here and in the other thread, but when you don't understand something, it doesn't seem that way. (it only becomes a simple concept after you understand it) By the same token, however, it's a bad tactic to present something as inherently mysterious simply because you don't understand it. The short answer to "why at the sunset do we see the sun rays converging towards the sun?" is because that's how perspective works. The important concept here is not about the sun's rays being parallel or nearly so, it's that the rays reaching our eyes from different points are not parallel. There is an angle between different non-radially--aligned points in our vision. The size of an object in our vision is a function of that angle and the distance to the object. The objects looks smaller when they are more distant, because the angle is smaller. You want more? Then study up on the geometry of vision and perspective. It's an important concept, because it's why we can have solar eclipses, even though the moon is far smaller than the sun.

I didn't say there was a dependence on the intensity. I said there was a dependence on the spatial behavior (specifically, radial) of the intensity. Your sketch is not to scale (which is consistent with this whole charade; see Sensei's comment), but even so, your lines are not parallel, as you admit. So this cannot possibly be a defense of the claim that light rays are parallel. We can treat the light as being parallel as a first-order approximation, but claiming that they are actually parallel is a stronger statement, and not true.

We know this? That would imply that the sun's intensity is constant with distance, rather than dropping off as 1/r^2 Do you have any physics to support this claim? The fact of the matter is that the rays are divergent, but with a very small angle Train tracks are parallel. They appear to converge in the distance. It's perspective/geometry, as discussed recently in your other thread. The angular separation gets smaller with distance, while the linear separation is constant.

But lengths measured by the ship are actually shorter than lengths measured by a stationary observer. If you measured the lengths between posts in your diagram (e.g. by bouncing photons off of them and measuring the time interval), they would be equal.

I don't have the book in front of me. I remember seeing the problem in the book, ~40 years ago when I took the class, and ~30 years ago, when I was a TA for the class.

But it's the same effect of geometry. Why is one acceleration and the other isn't? Because of geometry. The change in angle gets smaller as the distance increases (as Eise's drawing demonstrates). But acceleration is not defined in terms of angles.

What does that have to do with diffraction?

Does it? The sun's blackbody spectrum is consistent with the surface temperature, not the internal temperature. Photons from the hotter interior regions are absorbed before they reach the surface, and thus make no contribution to the observed spectrum.

IIRC there are problems like this in Halliday & Resnick (and no doubt in the later versions) with a rectangular cross-section. Making it a triangle just adds a little extra geometry to the mix.

Diffraction depends on the deBroglie wavelength, not the wave function. The deBroglie wavelength is dependent only on the momentum. Slits do not make this wave narrower.

Which is due to geometry, not acceleration. Notice how the poles are getting shorter, too. Is that supposed to be acceleration as well? No.

You can actually do the experiment with a compass... ! Moderator Note I warned you I would close this.

If an object is not gravitationally bound, it will always have greater than escape velocity. It speeds up as it gets closer to the sun (or other celestial body). Unless it’s a BH (so that it can’t escape) edit: xpost with Janus

That’s a start. That gives you the voltage. The resistance will change over time as the wire moves. Solve for I.

What have you done so far?

! Moderator Note Claims without evidence are bad enough, but yours contradict observation. Provide a basis for your claim, or this will be closed

If you want people to explain the underlying physics to you, you should clarify this. I was assuming you knew that already. Is there a force in the x direction? Are you aware of the connection between force and momentum? Seriously: if you don’t understand that you need to be tackling simpler problems first. I’ve been responding under the assumption that you wanted some pointers to solve the problem, not teach you physics or solve it for you. You can’t claim this while acting befuddled at first semester physics concepts

Yes. m1, m2 and the rod - all distinct from one another I’ve explained the boundary conditions. The system will conserve energy and the motion of one end is constrained. Momentum in the x direction will remain the same. But you seem to be questioning this.

You need to present a consistent model. m1 and m2 are the masses. The massless rod is separate.

They are connected by a rod.

Time isn’t a substance. It does not need to be created. Do you have a model?

Indeed. Back up your claims, or we’re done.

! Moderator Note And this is not going to fly ! Moderator Note And we’re done. Do not bring this topic up again

! Moderator Note I am unaware of your credentials, and in any case citations implies peer-reviewed literature. Besides, anyone who cites the “law” of common sense has damaged their credibility at the outset. This is a science site. We require scientific references and evidence.

Citations needed.