Science Forums

# DaveC426913

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1. ## Dart Trajectory

My favorite was one lady who stuck her first dart in the left scoreboard, and her second dart in the right scoreboard. She was not too pleased that I awarded her the title of having "the widest spread in the club". :)
2. ## Dart Trajectory

He is one of the best players in our club. Although that's really not saying much. We just dart for fun, though it is a tournament. At least half our players have trouble hitting the board thrice in a row. He only does occasionally, to keep both skillsets sharp. I'm not sure if he's much worse at underhand than overhand.
3. ## Is This True?

Yes. I'd say mentioning playing the film backwards is merely to give an image of : "This is what it would look like, if it happened in reality". Playing the film backwards is not literally part of the concept of thermodynamics they're trying to communicate to the reader.
4. ## Is This True?

Not in a closed system. It can increase in an open system (for example, sunlight added to Earth => complex life) But if you extend the boundaries of the system to include the sun, then the overall entropy is actually increasing. Another way to say this is that entropy can temporarily decrease locally in a system, but not globally.
5. ## Chaos In Colors

Not related to colours, but there are some non-repeating tesselations (tiles) - arrangements that never repeat on large scales. Pity, I cant seem to find an example. Must be Googling the wrong keywords. [ EDIT ] Ah. "Roger Penrose discovered that it was possible to construct a pattern from just two different shapes, each of them a rhombus with angles which are multiples of 36 degrees; the pattern achieves fivefold symmetry and, most remarkably, can be extended to infinity without repeating itself." https://www.wadham.ox.ac.uk/news/2014/january/non-repeating-patterns
6. ## Dart Trajectory

I dart with a guy who likes to throw underhand. The angle of impact is supposed to be more advantageous - essentially, the dart hits the board at the top of its arc - dead straight in.
7. ## Propulsion System With A Mathematical Problem.

Well sure. There's lots of ways. Heat them till they turn to a gas, they will expand enthusiastically. Make sure they are made of chemically-active materials, then they will heat themselves, turn to a gas, and expand enthusiastically. If there's a hole in the chamber, they will attempt escape - again - enthusiastically. If that hole is at the opposite end of the ship from the cockpit, all the better.
8. ## Propulsion System With A Mathematical Problem.

Yes. We simply call this reaction mass. You throw it out the back end of the rocket, and your rocket goes the opposite direction. The thing is, it doesn't get around the primary problems of rocketry: 1] storing all that mass (and thus moving it, as dead-weight) 2] accelerating that mass to a high velocity If the mass is not chemically active, then you need a device (motor) that accelerates it. And that device will need fuel to power it, Our solution is to use chemically-active mass. You don't need a motor to accelerate it - the energy is stored chemically within the mass itself - often
9. ## Propulsion System With A Mathematical Problem.

Without anything external to push against or ejecting mass, you cannot make a craft go anywhere. Basic Newtonian physics.
10. ## New Emd Propulsion System. Fast Space Travel.

It doesn't matter what you use, or how you use it. You can't use magnetic fields to move a spaceship through space.
11. ## Dart Trajectory

If it were falling faster than its horizontal movement then it would, by definition, have a downward trajectory greater than 45 degrees. That would not be a good throw. (see attachment) No, at the peak of the parabola it has zero vertical velocity. As you release, the dart has its highest upward (positive) vertical velocity - and a constant acceleration downwards (negative), which immediately begins canceling the positive velocity. At the top of the parabola, all its positive velocity has been canceled by the negative acceleration, and it is momentarily vertically at zero v. (plea
12. ## Dart Trajectory

I do realize that. Which is why I wouldn't - and didn't - suggest such a thing. I was talking merely about the contact.
13. ## Dart Trajectory

I'm surprised to hear that darts of the same set would not have identical weights. That's a real quality issue. It's probably too late to take them back. You can buy tiny weights to add to your darts. This would be a far better solution than trying to compensate. The key to accurate darts is consistency. You don't want to be changing your throw all the time. To my eye, the thing that most confounds amateur dart players is that they don't realize how much the arc affects their accuracy. A dart that hits the board closer to horizontal will have a much higher probability of hitting near i
14. ## Dart Trajectory

This is kind of strange. Since you acknowledge that you can't tell the difference in weights, it follows that you can't adjust your throwing force to compensate simply based on weight alone. Is this actually about you manually throwing darts? Or something else? If it's really about throwing darts, then why not do the experiment? Get a few darts of differing weights, throw them, and plot what effect you get. You'll likely notice that heavier darts fall shorter than lighter darts.
15. ## Yes, You Can Go Faster Than Speed Of Light

Awright. This is ridiculous. It's only been 13 hours!!!
16. ## Yes, You Can Go Faster Than Speed Of Light

He did not say that. "Not being able to find an inertial frame" is not the same as "all frames are accelerating". And you continue to cherry-pick fragments of quotes without bothering to understand the context.
17. ## Yes, You Can Go Faster Than Speed Of Light

Yes. Read what I wrote. Time dilation is a fact of an Einsteinian universe. That's how he wrote it. It makes sense to everyone else who is sufficiently familiar with it. You're doing it again. Your'e creating a mundane scenario, and using everyday logic to examine it. I'm gonna guess that travelling at relativistic velocities is not a everyday thing for you. As long as you try to rationalize relativistic physics using Newtonian absolutes of time and space you will encounter paradoxes. That's why Newtonian physics is insufficient to explain our observations at extreme velocities.
18. ## Yes, You Can Go Faster Than Speed Of Light

Please. Stop using everyday analogies. It goes without saying that relativistic physics is not the same as the fixed time / fixed space of Newtonian physics. You already acknowledge that time dilation is a fact of the world. (You just don't like the flavour.) So your old idea of "logically impossible" does not apply. Non-intuitive dilation is a fact of an Einsteinian universe. Accept it. This statement may well be true, inasmuch as you not having seen any prominent physicists. But no prominent physicists - seen by you or otherwise - have a problem without the apparent paradox.
19. ## Yes, You Can Go Faster Than Speed Of Light

The citizens of the 19th century thought 60mph trains and heavier-than-air craft were "logically impossible" until experiment showed that their assumptions were wrong. And that is what you are doing here. You've decided how you think SR works, and then declared it logically impossible. Frankly, I agree. As does the science community. Your idea of SR is logically impossible. Because your understanding of it is messed up. And no amount of arguing it will convince you - until you go back and pick up a book and read it.
20. ## Yes, You Can Go Faster Than Speed Of Light

This was how the Greeks thought. They thought the world should be deducible logically from first principles, with no need for experiment. They were right about a lot of things, but they were dead wrong about that. The universe does not care what you think is logically impossible. It is very a simpler matter of your logical premises being wrong.
21. ## Yes, You Can Go Faster Than Speed Of Light

Thanks, OB. That does actually provide some clarity, assuming you are correct in your assessment of his argument.
22. ## Yes, You Can Go Faster Than Speed Of Light

If this is where you're starting from; if this kind of analogy is what you're using to compare to relativistic velocities, then I stand by my assertion that this thread is insufficient to teach you physics from the ground up. Even in Galileo's time, relativity aside, they understood how it is possible to do perfectly good physics assuming that you are at rest while the Earth moves under you. They can, and they haven't had four centuries of knowledge like we have. Why can't you? But I'm so substitute for a high school education. No forum discussion is. You need to be untaught you first. I
23. ## Yes, You Can Go Faster Than Speed Of Light

You mean other than pointing everyone at the tests that have demonstrated excellent correlation with the theory (tests you don't know about, apparently). You've gone full science-denier. It jives with what I realized before. You're not arguing relativity; you're arguing your own pet idea of it. And being a science-denier would explain why you haven't bothered to read up on it. That's OK. I'm not here for you. I'm here to ensure the rest of the readers understand the difference between science and the fiction being peddled here.
24. ## Yes, You Can Go Faster Than Speed Of Light

Then you might want to correct it to say what you mean then.
25. ## Yes, You Can Go Faster Than Speed Of Light

(Giving you the benefit of the doubt here:) I'm sure you didn't mean to say this, but ... of course, no observer sees their own time being distorted. I'm sure you didn't mean to say this either, but of course, no one cites anything as proof (whether in quotes or not) in science. Confirmation would be the word you're looking for. The loops are for storage and acceleration. The test chambers are straight. That requires only a passing knowledge of particle accelerators. Even so, any non-inertial effects (such as due to rotation/revolution of the Earth) can be easily factored out.
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