# Recent content by Wonderballs

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....