# Recent content by blather

1. ### Is this considered as a function?

Oops! You win. "Relation." Apparently I forgot "relation."
2. ### Linear momentum conservation vs angular momentum conservation

Somewhat unclear, but that sounds good. Maybe? Are you trying to say that the conservation of linear momentum implies the conservation of angular momentum? In that case, I could buy into that. It might be preferable to show this more rigorously by making arguments that rigid rotators are...
3. ### A challenging sum series

Ah. Seems like you've got this one. I'm curious, could you post the solution when you get it? I'd be much obliged.
4. ### 1/f(x) graph

The easiest way to get this is to flip the x and y axes around. So, you could draw an imaginary line (like a dashed line) along the x-y line (45 degrees from the x-axis in quadrant 1 going through the origin). Then, take the lines under the dashed line, draw them on top like they'd be seen in...
5. ### Is this considered as a function?

It's the "general math" forum! The answer should be general! ;-)
6. ### Is this considered as a function?

I mean function like "mapping elements from a set A to a set B." (Rudin, 3rd ed.) You know? No bijectivity required.
7. ### Is this considered as a function?

Right, true. Yes, ok. Fine, but functions don't by definition need to be one-to-one. That's just an injective ("one-to-one") function. Restricting the domain to pass the vertical line test doesn't need to happen to define it as a function...just a one-to-one function. I thought if...
8. ### Particle picture is misleading. True?

Things also go faster than the speed of light. You know: from a contradiction, you can get anything. Best of luck.

10. ### Underdamped response

Right. The zero values don't help much. Pick a pair of peaked values.
11. ### A challenging sum series

That's neat! The square root of the imaginary term can be rewritten as i=e^{i\tfrac{\pi}{2}} \sqrt{i}=e^{i\tfrac{\pi}{4}} \sqrt{i}=\cos\tfrac{\pi}{4}+i\sin\tfrac{\pi}{4} \sqrt{i}=\tfrac{\sqrt{2}}{2}\left(1+i\right)
12. ### De Broglie wavelength neutrons

Time to celebrate.
13. ### Polar equation problems

Wait. Hang on. No. dv=-(1/2)\cos 2\theta d\theta
14. ### Polar equation problems

Yes, you're correct. But it is of no consequence because we don't need the differential of v.
15. ### Check my working for finding if vectors are parallel ?

Ok, we can use the same idea then. See if you can find a number that gets from one line to the other. I wouldn't use a cross product, but if I did, then I'd need to keep the constants. I'll also hazard that posting sort of opens you up to questions about process and understanding. The...