swansont

There is the additional caveat of going directly downwind. A sail won't do this.

Mass-wise this is a non-starter. It's basically conserved at this scale. The density issue is another thing. You want the opposite of a submarine filling the ballast tanks from the compressed air tank. The problem is that you are starting with a positive buoyancy, so you will always need that extra mass, regardless of the density, unless you can figure out a way for the human body itself to become more dense.

I think the first reaction is thinking the propeller is driven by the wind, and powers the wheels. Such a device would not go to faster than the wind, because the thrust would drop to zero when the vehicle speed and wind speed are equal. I think that's the initial reaction of the people saying it's impossible. These are losses and would initially be ignored. The first-order questions are what is the energy of the cart, and what is the energy extracted from the wind? At the point where you are going downwind at the speed of the wind, the speeds are equal. So the mass of the air involved must exceed the mass of the vehicle, which suggest you need a big propeller, since you want to maximize that mass difference. A big propeller means the "column" of air has a large volume.

Do you worry about this when eating food with your hands? Assuming that you wash your hands with soap, that it. The rinsing effort is similar, as is the risk of ingesting soap.

Plagiarism is passing off the work of someone else's as your own. It is a form of cheating - you are taking credit for someone else's work. Buying an essay is one form of plagiarism. In some cases it's the least useful form of cheating, since giving proper credit to the source shouldn't diminish your own work in any way.

Have you considered washing with soap and water, with proper rinsing afterward?

I recall a device claiming this perhaps 10-15 years ago. There was some controversy initially owing to some confusion about the description. It was a cart with a propeller that was driven by the wheels, but the propeller was sending air backward (so it was not the wind turning the propeller and providing energy to the wheels), which means the propeller was acting somewhat like a sail in capturing its propulsive energy, and also providing thrust. The propeller thrust depends on the ground speed, and as long as you capture enough energy from the wind it could work. So, big propeller, low mass. edit: link rot was thwarting me, but I finally tracked something down https://boingboing.net/2007/02/06/video-can-a-vehicle-.html https://www.youtube.com/watch?v=aJpdWHFqHm0

Surely that have contact info so you can ask them.

Possibly silicon. Whatever they used for a substrate.

You're going to have to give more information than this

I think I googled “name of indentation between bicep and tricep” First hit. (incidentally, mentioning that you’ve at least tried a search is worthwhile)

It’s hard to envision that just compiling others’ words would make for a coherent paper. Of course. We see that here in the HW section with people who just want the answers.

There’s nothing wrong with using pictures, drawings or passages made by others (sometimes it’s unavoidable) But you need to give citations for them, and not present them as your own work. A big part of the problem, IMO, is that they are given a pass early on. It also seems to me that the younger crowd was more prone to sharing music and ignoring copyright back when napster, etc. were big. Maybe there’s a connection.

Ah, Google “The space between the biceps and triceps forms two grooves (medial and lateral bicipital grooves)” https://www.kenhub.com/en/library/anatomy/biceps-brachii-muscle

No? I can see where I said it. “A shield as described would be send the net radiation perpendicular to the surface. Basically half would head to the earth.” That was part of my explanation as to why it wouldn’t work. I said “the shield as described” so it should have been clear what I was talking about

Not at all. I said net radiation. Anything at some non-normal angle would be canceled out, when averaged over the surface. No preferred direction in the plane of the reflector. At 1000 km above the earth? Show me the calculation.

The teachers did it? My impression is that plagiarism is given lip service in school, so it’s not taken all that seriously, until it is an actual problem, and then people are shocked that they are being punished. Kinda like My Cousin Vinnie - “You were serious about that?” It might stem from certain “only the results matter” attitudes, and pressure to succeed. Plus an attitude that it’s only wrong if you get caught. Even places with honor codes that are supposed to be hallowed tradition have cheating scandals. We spam-ban essay writing services on a regular basis. They must have customers out there.

Symmetry. There’s no preferred direction for the radiation, so it should be isotropic, and it’s a 2-D system. Why? How small is negligible?

A shield as described would be send the net radiation perpendicular to the surface. Basically half would head to the earth. The shield would also reflect radiation from the earth back to the earth. The distance doesn’t really enter into it.

! Moderator Note Threads merged

That’s the scenario from Prometheus’s post

If you mean the point about passing through shadow, it may be an issue of temperature fluctuations from doing so, and that you’d want to avoid that, so you don’t have to deal with returning to equilibrium Perhaps the angular momentum of being in such an orbit is an advantage.

I imagine the point of launching is that it doesn’t get in the way of doing things on the ground.

Geostationary orbit is equatorial https://en.wikipedia.org/wiki/Geostationary_orbit The tilt is why it won’t block the sun except when the sun is lined up over the equator

It only works a very small fraction of the time (near noon near the equinoxes), because it’s only over the equator The sun’s rays are very nearly parallel, so it’s about a square km A shield that was perpetually blocking the sun would heat up and radiate, reducing the effectiveness of the shield.