Physics - January 2007

I am doing a project in physics under the title photometer.
I would like all the information i can get about photometer,artificial lighting,shadows.
I searched the net but there are many useless links there but only some good links.
So i post this question on yahoo.
Please answer with even a line u know about photometer.
Even if it is a single good sentence i dont care

2007-01-20 12:32:45 · 5 answers · asked by !!!!! 2

does anyone know how fast hot air can move.

and can someone please give me the math/physics formula behind the speed and acceleration of hot air.

2007-01-20 12:25:44 · 1 answers · asked by Anonymous

2007-01-20 12:09:21 · 13 answers · asked by SweetPea 3

Atomic clocks are extremely accurate clocks that can measure billionths of a second. In 1971, scientists used these clocks to test Einstein's ideas. 1 atomic clock was set up on the ground, while another was sent around the world on a jet traveling at 600 mph. At the start, both clocks showed exactly the same time. After the jet returned though, it was a few billionths of a second behind.
Later in history scientists put 4 clocks according to the same atom out there; one in california, one on the east coast, one on a train and one on a jet traveling faster than the speed of sound. After the jet traveled around the world, faster than the speed of sound, the clocks on the west and east coast were the same. The clock on the train was 1 minute behind and the clock on the jet was a full 10 minutes behind.
Based on this theory, some scientists believe if you could travel at or close to the speed of light to and back from a planet, you would be gone 1 year, but 100 years on earth would pass

2007-01-20 12:06:22 · 5 answers · asked by Julia 4

Though I dont expect an educated answer I feel I must clarify. I am asking how they could know that the speed of light is the fastest velocity attainable without actually reaching the speed of light. is it noot probable that the fastest attainable speed may be slightly above the speed of light?

2007-01-20 11:42:39 · 9 answers · asked by Goo 1

Or is that out of the realm of science? In theory, it can be possible but in reality is this true? Is there any advances on technology for that purpose?

2007-01-20 11:22:42 · 8 answers · asked by Passion 3

Under coulomb's law, F=(1/(4π*permittivity of free space))((Q1*Q2)/r^2).
What are the units for F, Q1, Q2, r^2 and the permittivity of free space. And can someone explain the law to me. Will appreciate it very much. Thx in advance.

2007-01-20 11:20:00 · 1 answers · asked by Death Blade 2

I welcome any random tid bits of information or other sorces of information about the HLC.

2007-01-20 11:15:52 · 4 answers · asked by magpiesmn 6

A light wave has a frequency of 4.90 x 1014 cycles per second. What is the wavelength?

2007-01-20 11:13:36 · 5 answers · asked by dreamerloverlibra 2

I hear it so much, but I have no idea what it actually is!

In my notes, it says "a matrix with real eigenvalues", but this confuses me further. Perhaps I'm slow?

2007-01-20 10:50:18 · 7 answers · asked by sarciness 3

This video claims that the act of observing particles in the double-slit experiment makes the particles create a particular pattern on the back wall that they won't otherwise create.
http://video.google.com/videoplay?docid=-4237751840526284618
I read that it's not the act of observing that effects the particle, it's just that we can only observe particles that are hit by photons. But that doesn't explain why, if we don't MAKE photons collide with any of the particles, the back wall pattern is still effected by our observing (I mean, if we observe only particles that are hit by photons naturally).
What happens if we, in the future, become able to observe double-slit experiments made years ago on another planet? Imagine they took place some years ago, and the light has traveled to us during that time. Will those particles behave as though they were observed, although they cannot possibly "know" that we will observe them years later? What would happen?

2007-01-20 10:43:35 · 1 answers · asked by Justin Case 1

2007-01-20 10:40:40 · 7 answers · asked by rod 2

2007-01-20 10:05:49 · 4 answers · asked by Ellen T 1

2007-01-20 10:01:55 · 3 answers · asked by Ellen T 1

okay, we are doing some problems for physics..and im kind of lost...I need help because I have never taken a trig class in my life and this physics book I have doesnt help that much..heres the question.

1. A man walks 5 mi east, then 6 mi North and then 3 mi further East. Make a scale diagram of the man's path on graph paper.

I did this and got 14 mi.

part b) Calculate the straight-line distance from where the man started to where the man ends up. (Is this the same, grater than or less than your answer to part a.

I got 10 mi as my answer which is less than.

Now heres my trouble.

c) At his final position the man turns and points toward his starting point. What direction is he pointing? (Be clear and exact)

Okay I know to use inverse tan to get this and its 53.1 degrees west of south but im a bit confused, wouldnt this be the degrees of the angle, and it would actually be facing towards the opposite side and not towards the point that he started?

2007-01-20 09:48:25 · 2 answers · asked by hmmm 2

2007-01-20 09:48:18 · 1 answers · asked by jUgGaLette!!! 2

When you want to pull downward to lift something, the main advantage of passing a rope upward and through a single pulley, rather than just up over the branch of a tree, is that the pulley

a. generates some of the force for you
b. changes the pulling direction
c. makes the rope stronger
d. reduces friction

2007-01-20 09:43:55 · 2 answers · asked by Needs_help 1

Suppose a 1.82 g nugget of pure gold has zero net charge. What would be its net charge after it has 1% of its electrons removed?

2007-01-20 09:39:39 · 1 answers · asked by nt 2

(a) What is the composition in mole fractions of a solution that has a vapor pressure of 43 torr at 20°C?
(b) What is the mole fraction of benzene in the vapor above the solution described in part (a)?

2007-01-20 09:19:31 · 1 answers · asked by magicalplaygirl 1

What is an example of velocity and acceleration

2007-01-20 08:50:53 · 7 answers · asked by Anonymous

Here is a question i've had for a few years but have never asked. I'm sure there is an answer out there somewhere.

If you were to dig a hole straight through the middle of the earth, assuming that you could go through the rock and the fire, etc
So now there is a hole straight through from one side of the earth to the other, kind of like a donut.
Now you jump into the hole.
What happens? Do you blow up in the middle? Come out on the other side? Get stuck at the centre of earth? Answer this with your theory.

2007-01-20 08:35:07 · 7 answers · asked by Anonymous

why does resonance occur for the condition of an integral number of half wavelengths just fitting on the string?

2007-01-20 08:06:27 · 1 answers · asked by stumped on physics 2

Car A runs a red light and broadsides Car B, which is waiting to turn left. Car A has a mass of 2000 KG. Car B has a mass of 1500 KG. After the impact, the cars stick together and slide away at a speed of 9.1 m/s. How fast was Car A going when it hit Car B?

2007-01-20 07:51:31 · 2 answers · asked by BadRomance 2

The speed of light is said to be a constant.

Is the above a fact or an assumption since we cannot observe anything that moves faster than the speed of light?

( I would like answers from people who actually know this stuff, not just speculation )

2007-01-20 07:49:02 · 7 answers · asked by Gaga M 1

State the steps in the life of the following stars: Average Mass Star, Massive Star, Super Massive Star

2007-01-20 07:27:59 · 3 answers · asked by RJ 2

2007-01-20 07:27:46 · 4 answers · asked by rapxo 1

How is it the Sun does not have the highest absolute magnitude but has the highest apparent magnitude?

2007-01-20 07:26:21 · 4 answers · asked by RJ 2

2007-01-20 06:50:58 · 12 answers · asked by Anonymous

if sun has used 1/2 of its fuel during its life why the gravity of the sun is still keeping us in orbit
sorry for the improper experession of the question but i m just a cook

2007-01-20 06:48:33 · 6 answers · asked by mageros 3

Hi,

The surface charge density on an infinite charged plane is -2.2 x 10^-6 C/m2. A proton is shot straight away from the plane at 1.9 x 10^6 m/s. How far does the proton travel before reaching its turning point?

Any idea on how to start this one?


Thanks!

2007-01-20 06:18:49 · 3 answers · asked by Anonymous