Physics - March 2007

A Thermopane window consists of two glass panes, each 0.50 cm thick, with a 1.0 cm thick sealed layer of air between. If the inside temperature is 21.5°C and the outside temperature is 0.0°C, determine the rate of heat transfer through 1.5 m2 of the window. Compare this with the rate of heat transfer through 1.5 m2 of a single 1.0 cm thick pane of glass.
Answers:
J/s (Thermopane window) =
J/s (Single pane window) =

Thanks

2007-03-15 14:12:59 · 3 answers · asked by Anonymous

2007-03-15 13:58:36 · 8 answers · asked by Anonymous

the resistivity of copper is 1.7 x 10^-8

i think you're supposed to use the equation P=IV or P=(I^2)(R) or P=(V^2)/R but i'm not sure how to use them

2007-03-15 13:51:13 · 2 answers · asked by paulinatran10 1

An animal rescue plane flying due east at 36.0 m/s drops a bale of hay from an altitude of 60.0 m. If the bale of hay weighs 175 N, what is the momentum of the bale the moment it strikes the ground?

For some reason, in addition to the momentum the teacher gave me the angle at which it was below the horizon. Could someone please show me the work in detail to this problem? Please explain what all of your variables mean, just in case my text uses different variables.

Thanks!

2007-03-15 13:36:32 · 2 answers · asked by Jen 2

a car drove 72 miles per hour for 2 hours, then at 69 miles per hour for 5 hours. how many miles did the car go in all ?

2007-03-15 13:36:21 · 3 answers · asked by Anonymous

I can not find an answer for this. I look up the definition an electromagnetic field and it just describes it as being caused by "The electric field is produced by stationary charges, and the magnetic field by moving charges (currents); these two are often described as the sources of the field."

Now tell me this, is this cause theoretical or proven? Also, moving charges?? I always found physics to be very vague (I'm a genetics major). What do they mean by waves? Yes I took physics I know what a wave is. But HONESTLY what is a wave at the most subatomic level. For example in molecluar biology we can tell you how transcription occurs at the protein level.

I mean, what is radio waves?? How does a wave become music to our ears. I do know that our ears take in the waves and our brain processes each distinct series of waves as a 'sound' but how does do these series of waves travel so distinctly??

man I hope this doesn't come off as a bunch of rambling.. lol

2007-03-15 13:22:37 · 7 answers · asked by Ibrahim 3

the distance a spring stretches varies directly with the force applied to it. if a 6 pound weight stretches a spring a distance of 21 inches, how far will the spring stretch if a 10 pound weight is applied?

2007-03-15 13:16:10 · 5 answers · asked by Anonymous

You tie a cord to a pail of water, and you swing the pail in a vertical circle of radius 0.600 m. What minimum speed must you give the pail at the highest point of the circle if no water is to spill from it?

2007-03-15 13:07:46 · 1 answers · asked by DuDe 1

i have to build a rubber band car for distance.
is it better to have 3 or 4 wheels?
what is the reason for this, or does it matter?

2007-03-15 12:54:38 · 2 answers · asked by Anonymous

ok, the weight of the air in the atmosphere above ur head is quite great, why doesn't ur head get crushed? well, i somehow understand the physics concept, but i just can't explain it.T^T

help me please
thanks!

2007-03-15 12:49:12 · 7 answers · asked by Ganbatteru 3

Even if you draw a circle on a piece of paper, that circle has some thickness to it: the thickness of the ink or paper. If there are no 2-D objects, then does the second dimension really exist, or is it just hypothetical?

If 2-D -- the dimension we're most familiar with, other than 3-D -- doesn't exist, then what does that say about other dimensions, like 4-D?

And why is 4-D commonly thought of to be time? The other dimensions 1-3 are all about spatial relationships; why is 4-D so special that it diverges from that? (Rudy Rucker might argue that it's not time but simply an extra dimension tacked on to ours, like the Z-axis on the 2-D X/Y-axis.)

2007-03-15 12:31:07 · 6 answers · asked by no_good_names_left_17 3

the mass of it

2007-03-15 11:54:57 · 2 answers · asked by Anonymous

2007-03-15 11:52:26 · 1 answers · asked by cai 1

2007-03-15 11:46:02 · 3 answers · asked by Lorenzo de' Medici 1

Using salt

2007-03-15 11:40:22 · 7 answers · asked by Anonymous

2007-03-15 11:34:46 · 11 answers · asked by Anonymous

2007-03-15 11:30:05 · 3 answers · asked by Lorenzo de' Medici 1

2007-03-15 11:24:06 · 6 answers · asked by exxohh<3 1

The wavelength of light increases as it traverses the expanding universe between its point of emission and its point of detection by the same amount that space has expanded during the crossing time....

so both space and light are moving? expanding?
when i turn the light on in my room, is light and space moving
or only light?

2007-03-15 11:14:24 · 2 answers · asked by Lorenzo de' Medici 1

2007-03-15 10:56:30 · 1 answers · asked by Andrew 4

Tarzan, who has a mass of 60.0 kg, runs toward a lake at a speed of 5.00 m/s. He grabs a massless rope of length 10.0 m and begins to swing out over the lake, which is 20.0 m below. Taking t = 0 to be when he grabs the rope, at what time should he release the rope so he travels the greatest distance before hitting the lake? Assume the rope hangs just even with the edge of the cliff.

Bonus Question: What angle with the vertical does the rope make at this time?

I made this question up, and I'm pretty sure it has all of the needed information to solve it.

2007-03-15 10:54:02 · 2 answers · asked by Boozer 4

When they say that the amount of energy in a given amount of matter can be found out by the equation E=mc^2, do they mean *just* the energy found in that mass of matter, or do they mean the energy that would be released by reaction with an equal mass of antimatter, and therefore the amount of energy found in double that mass (the mass of the matter plus the equivalent mass of antimatter that would take part in the reaction)?

2007-03-15 10:52:40 · 4 answers · asked by Anonymous

A squirrel has x- and y-coordinates ( 1.30 m, 3.60m ) at time t1=0 and coordinates ( 5.20m , -0.300m ) at time t2= 3.50s
a)For this time interval, find the x-component of the average velocity.
b)For this time interval, find the y-component of the average velocity.
c)Find the magnitude of the average velocity.
d)Find the direction of the average velocity.

2007-03-15 10:51:48 · 3 answers · asked by Anonymous

Why does the Rainbow has a shape of an arc or a bow? Does it has anything to do with frequency or light?

Thanks!

2007-03-15 10:40:43 · 3 answers · asked by Kala J 3

ok im doing a report on coal energy and i need websites were i can find info so if you know any plz tell me thanks its due tomarrow im a slacker i know so plz help!!!!

2007-03-15 10:39:04 · 2 answers · asked by Anonymous

its for a class

2007-03-15 10:24:59 · 3 answers · asked by Preston D 1

i cant find this. The molecules in one form of matter move more rapidly that in any other form of matter. Where would you find this form of matter.

2007-03-15 10:16:01 · 7 answers · asked by Lindz 2

what would a current vs potential difference graph look like

2007-03-15 10:08:44 · 3 answers · asked by Anonymous

because i have motion-censored hand towel dispenser in my bathroom at school. i am in a stall, in the bathroom alone and the towel dispenser goes off.

***i am NOT debating the fact of ghosts!***

what could cause this if not a ghost?

2007-03-15 09:53:43 · 16 answers · asked by .:.:.Mizz_undaStood.:.:. 4

I just purchased a Microsoft Wireless Comfort Keyboard 1.0A. I enjoy working with it directly in my lap. Unlike a laptop computer it doesn't get hot and isn't heavy.

But my question is, does it give off radiation? (which could possibly damage my fertility etc.)

An answer from someone with a technical background, who understands radiation, would be great but any knowledgeable answer is appreciated.

Thanks!

Alistair McFeind

2007-03-15 09:43:07 · 1 answers · asked by Anonymous