Science & Mathematics - 18 November 2007

2007-11-18 09:55:12 · 3 answers · asked by Anonymous in Astronomy & Space

A fluorescent mineral absorbs black light from a mercury lamp. It then emits visible lights with a wavelength 520 nm. The energy not converted to light is converted to heat. If the mineral has absorbed energy with a wavelength of 320 nm, how much energy (in kJ/mol) was converted to heat?

I cant seem to visualize/get started on this problem, I imagine Ill have to find frequency to get the energy, but I dont see how ill end up with kJ/mol... Any help would be much appreciated.

2007-11-18 09:54:35 · 2 answers · asked by Coastal 2 in Chemistry

2007-11-18 09:53:33 · 2 answers · asked by johnny b 2 in Mathematics

Nobel laureate Richard Feynman (1918-1988) once said that if two persons stood at arm's length from each other and each person had 1% more electrons than protons, the force of repulsion between them would be enough to lift a "weight" equal to that of the entire Earth. Carry out an order-of-magnitude calculation to substantiate this assertion.

the answer is ~10^26N, but i don't know how to get this number.

2007-11-18 09:52:11 · 1 answers · asked by andrew w 1 in Physics

Metallic magnesium can be made by the electrolysis of molten MgCl2.

(a) What mass of Mg is formed by passing a current of 5.90 A through molten MgCl2 for 2.20 days? in grams

(b) How many minutes are needed to plate out 14.80 g Mg from molten MgCl2, using 6.60 A of current? in minutes

2007-11-18 09:50:55 · 3 answers · asked by softshimmer 2 in Chemistry

Why are some of the spaces for the elements empty?

2007-11-18 09:48:10 · 7 answers · asked by Anonymous in Other - Science

When you are a pilot for nasa, you dont really test or do experiments outside the ship, like space walk or anything else for research.Most of the pilots start out by flying planes in the navy or being a test pilot. What type of jobs or backround do the ones who test,spacewalk and other expirient astronauts have?


-if i am wrong about any of the information i said, please tell me

thanx!

2007-11-18 09:47:59 · 1 answers · asked by shhhhhhhhhhhhhh12344 1 in Astronomy & Space

Need some help with this:
10 square blocks, each of mass 1kg are to be stacked up on a floor to make a piloe 50cm high - assuming that the block are initially all lying on the floor and assuming they have the same dimensions, how much work is done in stacking up the bricks.

Can anyone help me with some guidance please!

2007-11-18 09:46:36 · 1 answers · asked by Anonymous in Physics

a sampe of sucrose, C12H22O12, is contaminated by sodium chloride. when the contaminated sample is burned in a bomb calorimeter, sodium chloride does not burn.

what is the percentage of sucrose in the sample if a temperature increase of 1.67 degrees C is observed when 3.000g of sample is burned in the calorimeter? sucrose gives off 5.64 times 10 to the third kJ/mol when burned.

the heat capacity of the calorimter is 22.51 kJ/degrees C

2007-11-18 09:45:30 · 1 answers · asked by belleswan 3 in Chemistry

2007-11-18 09:44:52 · 1 answers · asked by IbeME 1 in Chemistry

Ok, i'm having trouble putting the answer of this question into words:

The slope of a line in a graph is found where in an x/y table?

I know it has something to do with increasing and decreasing. Also, how would i make a made up problem that is similar to that? And finally, how would i explain it? Pleasseee, pleaseee help!!!

2007-11-18 09:44:39 · 12 answers · asked by ♥SuRfEr♥ 4Life 5 in Mathematics

I am applying thermal stress on a material with a melting point=160 degree centigrade, But in 95 degree after 3 days it changes to liquid (in lose capped vials). I think the name of this is melting but why in every reference even in Merck index it is stated that this chemical has a higher Melting point than 95?

2007-11-18 09:44:30 · 1 answers · asked by farnaz . 1 in Chemistry

Ten points will be awarded.

2007-11-18 09:44:30 · 3 answers · asked by Sandy 4 in Engineering

2007-11-18 09:44:18 · 5 answers · asked by jenjenryoung 1 in Mathematics

2007-11-18 09:42:05 · 4 answers · asked by Tonie M 1 in Mathematics

Please explain this to me. Thanx!

2007-11-18 09:41:58 · 2 answers · asked by Anonymous in Chemistry

Does anyone know where the circle was created, how it was created, who contributed to the construction of the circle, examples of circles today, and any interesting facts about the circle and its properties?

2007-11-18 09:41:12 · 8 answers · asked by mmholdford 2 in Mathematics

What is the distance to Earth?
What is the size?
How long would it take to get there?
What are some physical characteristics?
What would be some activities people could do when visiting this planet?

This is, of course, an imaginary project. The last question has to be something people could do, but if you were doing a planet with rigns you could do something like Ring Surfing or something...

2007-11-18 09:40:44 · 3 answers · asked by s¢яєαmjєssι¢α 1 in Astronomy & Space

rewrite in slope intercept form

2007-11-18 09:40:20 · 7 answers · asked by babriette r 1 in Mathematics

is the smoke relevant to the ratio of magnesium to oxygen (Mg:O) in the chemical equation, 2Mg + O2 = 2MgO?

2007-11-18 09:38:45 · 2 answers · asked by Anonymous in Chemistry

The weather man today said that there would be a 'flavour of winter' to todays weather.
So what flavour do you associate with winter?

2007-11-18 09:37:05 · 41 answers · asked by ooooooooo 3 in Weather

Specifically these formulas NaOH, CH3CH2OH , C3H8O, NH3 , NaOCl , NaCl, C12H22O11, CH3COOH, NaHCO3, H202, Na2C03,NaF.
Also i want to know if an atom can have multiple anions or cations for example C3H8O is it correct if I say it has one cation and two anion. Thank you

2007-11-18 09:35:23 · 2 answers · asked by hnz789 1 in Chemistry

2007-11-18 09:34:33 · 2 answers · asked by Hannah Banana 2 in Astronomy & Space

I have a couple of math problems that I believe are interrelated with physics, and I'm not really sure how to solve these problems.

A person drops a ball onto the dirt below. Use this position function to solve the problem: -16t^2 + (initial velocity)(time) + initial height

How high is the wall if the ball hits the dirt 3 seconds after the ball is dropped?

What's the velocity of the ball when it hits the ground?

Thank you very much for your help. I will give 10 points to the most correct answer.

2007-11-18 09:32:41 · 2 answers · asked by Celine 1 in Physics

I have a couple of math problems that I believe are interrelated with physics, and I'm not really sure how to solve these problems.

A person drops a ball onto the dirt below. Use this position function to solve the problem: -16t^2 + (initial velocity)(time) + initial height

How high is the wall if the ball hits the dirt 3 seconds after the ball is dropped?

What's the velocity of the ball when it hits the ground?

2007-11-18 09:31:56 · 2 answers · asked by Celine 1 in Mathematics

i'm not sure if this is true, can anyone prove this too me using a legitimate proof

2007-11-18 09:31:29 · 2 answers · asked by In Testimony Whereof 3 in Mathematics

This is the specific question that I was asked that I can't answer:

Carbon is a nonmetal, silicon is a metalloid, and tin is a metal. They are all in the same family. Yet, they all possess different behaviors! Why? If you can properly answer this question, then you truly have a grip on this unit.

Anyone know? Thanks :)

2007-11-18 09:30:45 · 1 answers · asked by Leslie 2 in Chemistry

10 points for best answer.

2007-11-18 09:30:22 · 1 answers · asked by Cherry 2 in Mathematics

I have a science report due tomorrow, two page min. four page max. (typed) The subject is Motion and Force. This is a list of all the things that must be included in the report. I've pretty much got the first part done
1. Description of what motion and force is
2. Description of different types of speed and examples of each
3. Description of different types of force and examples of each
4. Newton's 3 Laws of motion and examples of each
5. Any other interesting facts about the subject

If you get info off a website, I need sources!
Please help, I left all my notes at school and I'm doomed without you all.
By the way, I'm only 15, so I don't need college level info.

2007-11-18 09:30:02 · 1 answers · asked by Haley-bug 3 in Physics

A 23.0 kg box is released on a 37.0° incline and accelerates down the incline at 0.272 m/s2. Find the friction force impeding its motion.
____N
How large is the coefficient of friction?

2007-11-18 09:29:41 · 1 answers · asked by roofchelsea 1 in Physics