Recent content by ideasrule

I'm trying to teach myself celestial mechanics, particularly as it relates to spacecraft navigation. Essentially I'm interested in how spacecraft can get from A to B with the lowest delta-V (or whatever the criteria are), and how mission planners figure this out. Can anyone recommend a...

Interesting article. There's something very ironic about it: So when the prosecution says "there's a 1 in 4 billion chance that the DNA match is coincidental", what they actually mean is "there's a 1 in 3 chance that the stupid intern contaminated the crime scene DNA with the reference and...

U, B, and V represent a star's brightness in the ultraviolet, blue, and visible ranges, respectively. Here, brightness is measured on a logarithmic scale where lower values mean higher light output. So if U-B is low or negative, that means the star is bright in the ultraviolet compared to...

Microwaves and radio waves are both EM radiation with much longer wavelengths, but they're not practical to work with using a conventional Michelson interferometer. Actually, interference isn't irrelevant. Assuming you know the material's index of refraction, how does the interference...

See Torricelli's law: http://en.wikipedia.org/wiki/Torricelli%27s_law It's a remarkable theorem, with a very simple derivation. It should be enough to justify v1=v2, and finish part c.

I'm not sure either. Are you given any information about the z direction? You can't calculate volume if you only have information about 2 of the 3 dimensions.

We (or at least, I) treat everybody the same way, regardless of age. I think it was reasonable to assume that this was a homework question, because you posted in the "Homework & Coursework Questions" forum, whereas general discussion of physics should go here...

Using your method, you should get 1073 seconds. 6708/6.25 is 1073, not 1273. I can confirm that the answer should be 1258 s. (I actually got 1257 s, but the difference is negligible.)

I had to learn cursive in grade 4, but could never write faster in cursive than I could normally. After that, the only times I've needed the skill was when teachers wrote comments in either chicken scratch or cursive, or maybe a combination of the two, and I somehow couldn't ask them to...

I agree, but this is just a matter of semantics. Since the jury found her not guilty, she now has the same rights and responsibilities as an innocent person who was never charged in the first place. Under the law, she's innocent in all but name.

Mass is definitely not [length]^3 [time]^-2. That link is a crackpot website.

The question tells you that when a 5kg mass is hung on the spring, it stretches by 3cm. A 5kg mass applies a force of (5 kg)*(9.8 m/s^2), so can you find the spring constant?

I don't think it's wise to start thinking about semiconductors before understanding what happens in a conductor and insulator. Semiconductors are not simply half-way between conductors and insulators; they have many weird and wonderful properties that are too complicated to discuss before you...

If you compute that answer, you'll find that it's negative. That's because you calculated the work exerted by the spring on the external agent, not the work exerted by the external agent on the spring. Here's a useful way to approach this problem. We're applying a force to pull the spring...

What's the difference between the final velocity of the ball and its initial velocity? Remember that acceleration is just change in velocity divided by change in time.