Science & Mathematics - 10 December 2007

how do main sequence stars get on/off and what do they do on it

2007-12-10 11:46:02 · 5 answers · asked by lauren 1 in Astronomy & Space

If I have a list of presidents and when they were president, I can determine what years we had good presidents. If I have a list of presidents and where they were born, I can determine what locations produced good presidents. But if I combine that data, what good is it? So my question is how could data with both a time and spatial component be of any use?

2007-12-10 11:45:54 · 2 answers · asked by Aaron D 1 in Other - Science

A large rectangular room is 12.34m long. what increase in width will make the perimeter 5m longer if the length stays the same?

2007-12-10 11:45:45 · 6 answers · asked by hudson p 1 in Mathematics

when? etc..

2007-12-10 11:44:29 · 8 answers · asked by walker 2 in Astronomy & Space

I need help with these problems:

1. An airplane is at an elevation of 35,000 ft when it begins its approach to an airport. Its angle of descent is 6 degrees.
(a) what is the distance between the airport and the point on the ground directly below the airplane?
(b) What is the approximate air distance between the plane and the airport?

2007-12-10 11:43:34 · 2 answers · asked by Mia16 3 in Mathematics

Lim as x-->0 of (1-10x)^(1/x). Please show each step.

2007-12-10 11:43:31 · 1 answers · asked by IE 3 in Mathematics

OMFG!!! this is weird...any like scientific back up or ne thing??? it looks like it is moving very slowly, but to put it in poetic forms, it looks like a needle punctured it......i do live in the south east of america, so...yea.

2007-12-10 11:42:51 · 7 answers · asked by Anonymous in Astronomy & Space

Whats is its molecular formula?

2007-12-10 11:41:02 · 2 answers · asked by Mzbee 1 in Chemistry

Okay, so in my science class, we're studying waves.

Ex. Mechanical waves, electromagnetic waves, transverse waves, etc...

My group conducted experiments with a slinky (did I spell that correctly?) and we're suppose to demonstrate amplitude, compression, and constructive interference.

What type of wave is it when the slinky slides up and down along the floor? Sine wave, cosine wave, or does it depend on the way we move it?

I know that cosine waves start off with the crest at the y-axis, but I'm not quite sure of it in the real world.... Can't really explain how I don't understand xD!

And this is just something that came up on my interest, but how do I find the amplitude of the following?

y = sin x + 2sin 2x
y = sin 3x + cos 4x
y = cos 6x + cos x

Do I have to use identities?

Thanks.

2007-12-10 11:40:43 · 3 answers · asked by UnknownD 6 in Physics

100.0 liters of water steam collected at 127.0 degrees celsius ( under 1 atm) to ice at -20.0 degrees celsius. (Molar mass: O = 16.00 g, H = 1.008 g. The specific heat of ice is 2.03 J/g-degrees celsius, the specific heat of water is 4.184 J/ g- degrees celsius, the specific heat of steam is 1.99 J/g-degrees celisius. the heat of fusion is 6.01 kilojoules for water, and he heat of vaporization is 40.79 kilojoules for water)


please show the steps

2007-12-10 11:38:34 · 1 answers · asked by peluc 1 in Engineering

Lead will react with hydrochloric acid to produce lead (II) chloride and hydrogen. How many moles of hydrochloric acid are needed to completely react with 0.36 moles of lead?

How would I go about solving this problem?

2007-12-10 11:37:57 · 4 answers · asked by Anonymous in Chemistry

at t=0 a .755kg mass at rest on the end of a horizontal spring (k=124N/m) is struck by a hammer which gives the mass an inital speed of 2.96m/s determine the postion as a function of time and find the total energy

2007-12-10 11:37:06 · 1 answers · asked by Erin S 1 in Physics

ok, Na+H20 = NaOH + H2

2007-12-10 11:35:26 · 10 answers · asked by jessiisababe1212 1 in Chemistry

i can only use these numbers

2007-12-10 11:35:03 · 4 answers · asked by no name 1 in Mathematics

The smallest constant force that must be applied to stop it in 20 seconds is?

2007-12-10 11:33:23 · 3 answers · asked by Anonymous in Physics

"When a food or drink molecule binds to a sweet or a bitter receptor, an intracellular "second messenger" system (usually using cyclic AMP) is engaged."

what's an intracellular 'scond messenger' system?

2007-12-10 11:32:09 · 5 answers · asked by C'est Comme Un Rêve 3 in Biology

1sodium oxide, NaO
2barium nitride, BaN
3cobaltous chloride, CoCl3
4stannic fluride,SnF4

2007-12-10 11:32:07 · 4 answers · asked by basketballrules420 1 in Chemistry

i think that it is x=100^-.37t but would like to know if my work is right plz

2007-12-10 11:31:25 · 2 answers · asked by jaja_juice 1 in Mathematics

i have an essey due about him and i dont know exactly how he fits in biology can ne 1 help me

2007-12-10 11:30:25 · 2 answers · asked by farfaraway 2 in Botany

2007-12-10 11:30:20 · 7 answers · asked by kimberly b 2 in Astronomy & Space

2007-12-10 11:24:54 · 3 answers · asked by deb0708 1 in Mathematics

I first I was sure it was a comet but it faded pretty fast . also has changed against background stars many degrees in the past half hour now 7:30 just west of cassiopia and fading fast. I'm in Northern Maine

2007-12-10 11:24:31 · 8 answers · asked by oldtreeplanter 2 in Astronomy & Space

Under which operation is the set of positive real numbers not closed?
(1) addition
(2) subtraction
(3) multiplication
(4) division

2007-12-10 11:24:15 · 4 answers · asked by ☮ 5 in Mathematics

with what part of the human system does the pancres work?

2007-12-10 11:24:12 · 6 answers · asked by Anonymous in Biology

*something* really funky happened over my housee... idk what it was. but my dad saw this weird smudge in the sky and stuff like that fasinates him so he went and got his bonoculars and he showed my family... it looked like a tornado or some kind of funnel and it like sparked...
i thought maybe it was some sort of jet that broke the sound barrier, but i have no idea.
and i'm not some hick who would make something up

2007-12-10 11:22:43 · 8 answers · asked by Anonymous in Astronomy & Space

Question One ---. A 0.024 kg ball is dropped to the floor from a height of 1.75 meters. Just after the impact with the floor, the ball has an upward velocity of 5.2 m/s. If the ball was in contact with the floor for exactly 0.023 seconds, find the following:

a.) The impulse delivered to the ball, from the floor.
b.) The average force of impact.

Question TWO --- Two identical objects A and B of mass 4.0 kg move on a horizontal and frictionless surface. Object B initially move to the right with a speed of 0.5 m/s. Object A initially moves to the right with the speed of 1.5 m/s, so that it collides with object B.

a.) Determine the total momentum of teh two cart system.
b.) A student predicts that the collision will be totally inelastic (they stick together after the collision). Assuming this is true, determine the velocity of each object immediatly after the collision.

PLEASE HELP
YOUR HELP IS GREATLY APPRECIATED!!!!

2007-12-10 11:22:38 · 1 answers · asked by mimi j 1 in Physics

Is there diract propotion between time period of a planet to the plant's distance from the sun ?

2007-12-10 11:21:40 · 4 answers · asked by :-) 2 in Astronomy & Space

What happens to the brightness, voltage and current of the bulbs as more bulbs are added in parallel? Why?

2007-12-10 11:20:08 · 3 answers · asked by sunita s 1 in Physics

please dont solve it for me!! (its not for hw but if i get it right 15 bounus points will be added to my grade and bring it froma c+ to a b+...wich is MUCH BETTER:D..but getting that much bounus points with out working would just not be nice)
just tell me how to solve it if you can

a^2=b^2+c^2-2bc(cos A) solve for b

***^2 means squared
***you will have to use the quatdratic formula
***you will use square roots

if anyone helps me with this you are my hero!!

2007-12-10 11:19:40 · 6 answers · asked by mydadisageek 2 in Mathematics

i couldnt find any info on this comet if ne1 knows anything about it please let me know

2007-12-10 11:18:00 · 10 answers · asked by taylor2459 2 in Astronomy & Space