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Stefan-Boltzmann Law |
2009-12-28 |
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From florence:
Hi-
I have a college tutor and we are stumped with this question.
Assuming a filament in a 100 W light bulb acts like a perfect blackbody, what is the temperature of the hottest portion of the filament if it has a surface area of 6.3 X 10^-5 m^2? The Stefan-Boltzmann constant is 5.67 X 10-4 W/(m^2 X K^2.\
Thank you for your help. If you can only answer one question per day please answer this one and guide me through a solution.
Answered by Janice Cotcher. |
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Elements of a Matrix |
2009-12-28 |
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From peter:
I have a array of 10 by 6 I would like to know how to find the terms 11 12 and tell me de formula the array is:
23 03 01 05 03 08 02 06 03 06
24 04 08 09 04 25 13 15 05 08
26 09 19 12 06 31 22 29 16 21
31 10 24 22 15 32 34 33 27 24
32 32 25 33 30 34 35 34 31 35
Answered by Janice Cotcher. |
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The Snail Problem |
2009-12-28 |
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From kishore:
A snail starts crawling from one end along a uniformly stretched elastic band.
It crawls at a rate of 1 foot per minute. The band is initially 10 feet long
and is instantaneously and uniformly stretched an additional 10 feet at the end of each minute.
The snail maintains his grip on the band during the instant of each stretch. At what points in time is the snail
(a) closest to the far end of the band, and
(b) farthest from the far end of the band?
Answered by Janice Cotcher. |
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Related Rates of a Cylinderical Trough with a Horizontal Axis |
2009-12-26 |
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From Emily:
A cylinder is lying on it's side and being filled with water at a constant rate. Let the current height of water be t=0. When t=4, the cylinder is half full. When t=12, the cylinder is completely full. When is the rate of the height change increasing?
Answered by Janice Cotcher. |
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Finding Density Given Volumetric Thermal Expansion Coefficient |
2009-12-26 |
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From florence:
Hi-
Please help me to apply the formula for this problem. The coefficient of volumetric for gold is 4.20 X 10^-5 C degrees. The density of gold is 19,300 kg/m^3 at 0.9 C degrees. What is the density of gold at 1050 degrees C.
Could you please explain how to get the solution of 18,500 kg/m^3
Thank you for your help
Florence
Answered by Janice Cotcher. |
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Triangles on a base of 2.4 meters |
2009-12-26 |
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From Allan:
Please,How do I calculate the height of a triangle when I only know the width of the base line,It is 2.4 mtrs.
Thankyou very much.
Answered by Penny Nom. |
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Truncated Octagonal Prism |
2009-12-26 |
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From freitas:
the top plane of the truncated octagonal right prism is 45 degree with respect to horizontal. find the volume
Answered by Janice Cotcher. |
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Finding Specific Heat of a Substance |
2009-12-26 |
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From erin:
Hi-
2 kg metal requires 1.00 X 10^4 J of heat to raise its temperature from 20 degrees C to 40 degrees C. What is the specific heat capacity of the metal?
Answered by Janice Cotcher. |
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15 golfers 3 rounds fivesomes |
2009-12-23 |
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From Dewey:
I have 15 golfers playing 3 rounds of golf. We will be playing in fivesomes. Any formula that has everyone playing with a different person each round?
Thank you.
Dewey
Answered by Robert Dawson. |
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Perimeter |
2009-12-23 |
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From Jalyn:
I'm doing this math project comparing measurements and I want to know the perimeter of the Upper Peninsula of Michigan. Please Help me!
-Jalyn
Answered by Robert Dawson and Walter Whiteley. |
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triacontaèdre rhombique |
2009-12-22 |
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From Paul:
Je voudrais savoir si les quatre polyèdres suivants sont le même:
P1:c'est le polyèdre convexe de centre O dont les sommets (62)sont les projetés
(sur la sphère de centre O et de rayon 1,i.e U), des sommets(12), des milieux des
arêtes(30),et des centres des faces(20) de l'icosaèdre de Platon (de centre O);
P2::c'est le polyèdre convexe de centre O dont les sommets (62)sont les projetés
(sur la sphère de centre O et de rayon 1,i.e U), des sommets(20), des milieux des
arêtes(30),et des centres des faces(12) du dodécaèdre de Platon (de centre O);
P3:c'est le polyèdre convexe de centre O dont les sommets (62)sont les projetés
sur U des sommets du disdyakis-triacontaèdre (dual polaire du grand
rhombicosidodécaèdre)(de centre O);
P4:c'est le polyèdre convexe de centre O dont les sommets (62)sont les projetés
sur U des sommets (32) et des centres des faces (30) du triacontaèdre rhombique
(dual polaire de l'icosidodécaèdre) (de centre O).
Merci pour la réponse, et bonnes fêtes.
Paul
Answered by Robert Dawson and Chris Fisher. |
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A Lagoon, free form, inground swimming pool |
2009-12-22 |
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From donna:
What is the linear footage of a 14 x 23, Lagoon, free form, inground swimming pool?
Answered by Robert Dawson. |
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The tens digit of 0! + 1! + 2! + 3! + ... + 2000! |
2009-12-21 |
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From Alicia:
What is the tens digit of 0! + 1! + 2! + 3! + ... + 2000!?
Answered by Robert Dawson and Penny Nom. |
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Figure out the square root of something |
2009-12-20 |
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From eric:
is there an ez equation to figure out the square root of something?
Answered by Harley Weston. |
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Two percent |
2009-12-20 |
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From Brian:
Hello I am having a problem figuring out something. Someone told me that .98 is the same as 2% how is this possible, how did they figure this out
here is my example 929.79 x .98 = 911.19, is the same as 929.79 x 2% = 18.59, now minus the 18.59 and you will end up with 911.19, how did they convert 2%
to .98, please help thgis is driving me nuts as I am not very good at math. Thank you
Warmest Regards
Brian
Answered by Penny Nom. |
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