# Search results

1. ### Finding golf balls in the rough (ultrasonic idea)

I believe ultrasound requires a certain density medium to effectively travel through and get a response. Although the transmitter/emitter is probably adjustable... This is just an assumption based on the ultrasound probes used to check out fetus's (feti?) shape and size during pregnancy. I...
2. ### High speed electric motor

I don't know for certain, but some hard drives have motors in that speed range. Unfortunately I don't know any specifics on how to obtain one without obtaining it yourself. (ie. deconstruction) Also I am not sure how much torque a hard drive motor is capable of. Good place to start though!
3. ### Can this work ?

Now I know this won't work, but somebody had posted that any metal would work in conjunction with one magnet. Would it be possible to replace one of the magnets with a piece of steel, and have the other magnet "pull up" on the piece of steel which is also attached to the box. The scientist in...
4. ### Trig derivatives

I got it, thanks guys 1/13 e^2x (2sin3x - 3cos3x) = integral
5. ### Trig derivatives

I tried it with u = e^2x ; dv = sin3xdx I think i got the multiple and im stuck here: = -1/3e^{2x}cos(3x) + 4/9\intsin(3x)e^{2x}
6. ### Trig derivatives

Homework Statement \inte^{2x}sin(3x)dx Homework Equations integration by parts formula The Attempt at a Solution = 9/10e^{2x}(sin(3x)-1/3cos(3x)) I don't think I am taking the derivative of sin(3x) correctly thanks for taking a look :)
7. ### The Origins of the Universe?

Thanks guys, I just call them as I see them.
8. ### Solid fuel combustion engine?

Yes I belive mythbusters tried many variations to this kind of engine and none of them could reload the combustion chamber fast enough.
9. ### The Origins of the Universe?

Mkay,thanks i guess.
10. ### The Origins of the Universe?

So I stumbled upon a video on the internet which made an analogy of mass creating a curve in the blanket of spacetime in which objects of smaller mass rotated about it. Which lead me to belive this is gravity. But aren't there billions upon billions of things within the universe which have mass...
11. ### Good calc books

I bought a book called the "humoungous book of calculus problems" by: micheal kelley. I found this book a good asset for helping me to understand what is in my coursebook. However you really need to cover up the solutions as this book dosent offer any problems to do by yourself. Every problem...
12. ### How'd they figure that? (logic puzzle)

I have been looking over this in my head for quite some time, and I just can't figure it out. I'm not convinced that even if ONE of them commited suicide that the rest would follow suite.... and I definetly don't understand why they ALL do it on the 200th day.
13. ### How'd they figure that? (logic puzzle)

I still don't understand why after 800 days they commit, or after the foreigner gets washed away they suddenly know what colour theier eyes are even though it stated that he didint specify whose eyes were green. Which is exactly why its a brain teaser
14. ### Prof = Wrong?

is it called the binomial theorm?
15. ### Prof = Wrong?

(x^3-1)=(x^3+x^2-x^2+x-x-1) =(x^3+x^2-x^2)+(+x-x-1) =-1(-x^3-x^2+x^2)-1(-x+x) =-1(i dont know....
16. ### Prof = Wrong?

Lol, thank you on my paper i have it written down as (x-1)(x^2-x+1)... But I am still wondering how you get from (x^3-1) TO (x-1)(x^2+x+1) I have tried to factor by grouping but that got me nowhere...
17. ### Prof = Wrong?

Homework Statement lim |x-1|/x^3-1 x-->1+ Homework Equations The Attempt at a Solution This is from a "practise test" and the prof wrote his solution on it... I'm having a hard time figuring out why (x^3-1) = (x-1)(x^2+x+1) which is what he used to find the limit...
18. ### Cat in a box paradox

I may not know much about this stuff, but if you do not know the cats state, the box remains closed restricting the gain of such knowledge. Like lim x --> a . The funky smell was a joke.
19. ### Cat in a box paradox

If you know the cats state, the box has been opened (even if the box remains closed). So the box will always remain closed. Unless you smell something funky which opens the closed box that is still shut.
20. ### Hypothetical question on Inertia

It would behave exactly as you described, no resistance to motion. Happy??
21. ### How'd they figure that? (logic puzzle)

A. Why are they trying to kill themselves? You all assume they want to know what colour thier eyes are and want to commit. B. I don't get either part of the question.
22. ### 8 balls, 2 weighings

You never specified which president was playing the match, you could have a variable of answers depending on your own political views.
23. ### Temporary adhesive needed for a page turning machine

This is probably a wild idea, but maybe a charge inducer that could be turned on/off with an oppositely charged bar to move accross the page. Although, it has a high chance of not working; its worth speculating. :)
24. ### Temporary adhesive needed for a page turning machine

Maybe use a roller + fan?
25. ### Infinite Acceleration

/i think he is refering to the fact that he never stops accelerating...ever.
26. ### Does the shape of the curve, that is produced in space by a mass, have a name ?

I thought gravity was the curve produced in spacetime...
27. ### Infinite Acceleration

I was just being particular about the way you worded your statement, you had said "Let 10 MORE years go by", meaning you dont turn around after the 10th year only on the 5th, 15th and 20th.

Thank you
29. ### Speed of light

If I we're to travel around the EARTH at the speed of near-light for 10 earth years would i have aged 10 years?
30. ### Phantastic Photons

Are photons released from a lightsource at a particular rate? Im pondering this because i got the idea if a laser pointer were attached to a rotating cylinder and rotated at the speed of light (impossible I know) I wonder what the image the laser beam would produce on the wall?