Science & Mathematics - 20 September 2007

If r(t) * r(t) = c, then r(t) * r'(t) = 0.

r(t) is a vector valued function, and r'(t) is its derivative. c is a constant. The * indicates dot product (not sure what else to use).

I don't need a whole proof (it would be nice though), but an idea of where to start would be very helpful. A proof in two dimensions (as opposed to three) is all I need. Thanks in advance.

2007-09-20 14:03:54 · 2 answers · asked by Eric W 2 in Mathematics

2007-09-20 14:03:31 · 9 answers · asked by Anonymous in Astronomy & Space

i have an A&P test tomorrow and we do not have a study sheet for the leg muscles or arm muscles, we have a list of the ones we need to know, but no way to study them... we only have to know sartorious, pectineus, adductor longus, semimembranosus, semitendonosis, biceps femoris, gluteus maximus, vastus lateralis, plantaris, achillis, and cruciate. we have to know all the arm muscles. do you know any study websites that i could use i really don't have time to search for a good one..

2007-09-20 14:01:12 · 5 answers · asked by Anonymous in Medicine

I know this should be separated into 2 problems in order to solve it. but I've been stuck on where to start, so help. Please?

An inattentive driver is traveling 18.0m/s when he notices a red light ahead. His car is capable of decelerating at a rate of 3.65m/s^2. If it takes him .200s to get the brakes on and he is 20.0m from the intersection when he sees the light, will he be able to stop in time?

2007-09-20 14:00:55 · 4 answers · asked by Mimi 1 in Physics

Lately I have found everything about space to be absolutely fascinating. It just occured to me that the farther from the sun we travel gravity changes and so does time, but the physics that control these variables always stays the same. Or at least thats how it seems from my prespective.

Now I understand that we are about 20 years or so, as predicted by NASA from passing through the heliopause or the boundry line of where intersteller space begins.

Now to my knowledge, intersteller space is defined as being matter, or space that is taken over by other stars solar winds and other energies.

Once this boundry is crossed, do you think our understanding of todays physics will break down?

What are the possibilities if we could reach a galaxy with completely different physics than out own?

I hope that I have explained my question good enough for everyone to understand what I am asking. Space and intersteller space is mind boggling!

2007-09-20 13:59:42 · 4 answers · asked by Anonymous in Physics

Could someone help me with this?? There is also a correction to the question: fn(0)=0

So when x= 0 fn(x)-->0
when x = 1/n² fn(x)-->+∞
when x=1/n fn(x)-->0

I don't know where it changes over from +∞ to 0 again. It's somewhere between 1/n² and 1/n but how do I figure that out??

Also if you can help with the other parts... that would be awesome!

http://i21.photobucket.com/albums/b273/q_midori/rahw2-4.jpg

2007-09-20 13:57:37 · 1 answers · asked by Anonymous in Mathematics

FILLED ALL THE WAY TO THE TOP!

2007-09-20 13:56:23 · 2 answers · asked by Anonymous in Other - Science

If so, can a breastfeeding mother make her baby sick? I was stung by a bee, the area became very swallon and I have not been 100% since, however, my nursing 6month old daughter has been very unsettled since and cant keep anything down. I asked the pharmasist, and they just looked at me like I was stupid... it seems very suspiciously linked... could this be true?

2007-09-20 13:54:59 · 4 answers · asked by MJC 2 in Chemistry

Does anyone know part of an atom has the highest density?

2007-09-20 13:54:47 · 10 answers · asked by tkdsl101 2 in Chemistry

Maximize Sales= 3X1 + 2X2 + X3

Subject to: X1 + X2 + 2X3 ≤ 10
2X1 + X2 + X3 ≤ 20
3X1 + X2 ≤ 15

X1, X2, X3 ≥ 0

QUESTION: Set up the initial simplex tableau. . .
thanks..

2007-09-20 13:53:38 · 3 answers · asked by odoiii 2 in Mathematics

I need to know how i should go about handling a collision.
I can detect that the collision has occured, but by stopping the player completly normaly means it looks bad or i get stuck on the object. I need to know how to go about making it Slide across the surface when it collides on a angle, using the objects Vector3 Position, Vector3 Velocity ect...

2007-09-20 13:53:29 · 1 answers · asked by Anonymous in Physics

school project...

2007-09-20 13:51:29 · 2 answers · asked by Grace N 1 in Botany

and the same for 26 meters and 5 millimeters? thank you!

2007-09-20 13:49:31 · 4 answers · asked by k o 2 in Mathematics

I've been labouring over this for about a week, but I can't get my head around radixes. I need a clear, SIMPLE explanation.

2007-09-20 13:48:57 · 8 answers · asked by Anonymous in Mathematics

make about why this cell appears to have two nuclei?

2007-09-20 13:48:32 · 3 answers · asked by Noname 1 in Other - Science

2007-09-20 13:48:04 · 6 answers · asked by Sami 2 in Astronomy & Space

Have a friend hold a ruler by one end, letting the other end hang down vertically. At the lower end, hold your thumb and index finger on either side of the ruler, ready to grip it. Have your friend release the ruler without warning. Catch it as quickly as you can. If you catch the ruler 6.8 cm (~2.7 inches) from the lower end, what is your reaction time?

2007-09-20 13:47:34 · 1 answers · asked by Sanyok 1 in Physics

I need help proving how the curvature of a curve given by the vector function r is k(t) = |r'(t) X r''(t)| / |r'(t)|^3.

The proof starts out like this... (btw, T = unit tangent vector)

Since T = r' / |r'| and |r'| = ds/dt
r' = |r'|T = (ds/dt) T
Apply product rule you get:

r'' = (d^2s/dt^2)T + (ds/dt)T'

I don't know what to do after. Any help?

2007-09-20 13:46:01 · 2 answers · asked by Axis Flip 3 in Mathematics

i've read about making a small one using butane but i want to stick to the safer solvent, c02. plus the butane one is too small volume. I want 10L plus. I plan on adapting a large pressure cooker. i've learned that the critical pressure for co2 is 1100 psi, which is higher than it comes in the canister. if i heat the cooker while pressurising it will i achieve the pressure? the critical temp for co2 is 88F so i have to stay above that anyways. if i know what i'm talking about so far, i could heat the pressure cooker while pumping co2 into until I achieve the right pressure and temp at which point i could open a valvue at the bottom of the cooker at a rate that stays above critical.. will it work? is there a better way? am i doing anything dangerous or illegal without a licence? any answers appreciated.

2007-09-20 13:43:17 · 2 answers · asked by Anonymous in Engineering

How would you figure this out?

2007-09-20 13:42:59 · 4 answers · asked by Anonymous in Mathematics

What is the value of t?

I'm bloody awful at algebra. ):

2007-09-20 13:42:21 · 13 answers · asked by Rawrr 1 in Mathematics

just wondering

2007-09-20 13:41:38 · 1 answers · asked by macgyver 1 in Engineering

What senses do they use to achieve the finding of their specimen? Do different types of mosquitos use different types of senses?

2007-09-20 13:41:11 · 2 answers · asked by penguin 1 in Biology

and if they do, HOW do they do it? What about insects? Can flies masturbate? How about birds?

2007-09-20 13:38:15 · 32 answers · asked by Anonymous in Zoology

and how do i know when the atom is stable

2007-09-20 13:37:44 · 2 answers · asked by Anonymous in Chemistry

2007-09-20 13:37:14 · 2 answers · asked by Terri L 2 in Biology

I really need to know this by tomorrow evening b/c im leaving for a trip

2007-09-20 13:36:55 · 2 answers · asked by Viki 3 in Weather

2007-09-20 13:34:15 · 1 answers · asked by Terri L 2 in Biology

2007-09-20 13:33:19 · 3 answers · asked by Terri L 2 in Biology

2007-09-20 13:30:23 · 3 answers · asked by paul b 1 in Astronomy & Space