Physics - June 2007

2. UV is responsible for sun tanning. Find the wavelength (in nm) of a UV photon whose energy is 6.4 x 10^19 Joules. What part of the UV spectrum is this?

3. Surfaces A and B are irradiated and are observed to emit IR, and UV light respectively. What electromagnetic wave would the incident radiation be for surface A and for surface B? Explain.

4. Why do Astronomers say that viewing an event like supernova or any celestial object such as star is looking back in time?

5. How long ago in years did the supernova occurred?

6. The brightest star in the night sky is Sirius. It is estimated to be 8.3 x 10^16 meters from earth. When we look at this star, how far back in time are we seeing it? Express your answers in years. Assume 1 yr. = 365.25 days

2007-06-26 02:31:02 · 9 answers · asked by Anonymous

which is the +ve and which is -ve?

2007-06-26 02:23:22 · 5 answers · asked by Wambua Daudi 1

Could someone explain in words(no need to go too deep only need the basics) and not in maths how refraction occurs due to a change of wave speed as the wave moves from one medium to another.

2007-06-26 02:17:58 · 2 answers · asked by walt 2

photon needed to supply a given amount of heat greater than or smaller than the number of visible photons? Explain.

Concept- Energy and Electromagnetic Heat is a form of energy. One way to supply the heat needed to warm the object is to irradiate the object with electromagnetic waves. The object feels warm because it absorbs heat energy also referred to Infrared Radiation.

2007-06-26 02:13:56 · 2 answers · asked by Anonymous

Okay, I have a real basic understanding of how particle accelerators ( "atom smashers" for us older folks ) work. I know you shoot two beams of protons into a big racetrack ( basicallly ) in oppsosition to one another, use big ol' magnets to make them go really really fast, then when they hit they pop apart and make all kinds of cooky sub particles, perfect liquids, nuons, and other scientific ...er.... small stuff.

Ok, anyway, I have always wondered where the proton that these guys shoot around the racetrack come from? Do they have a buckets of protons lying around? Do they make tweezers that small?

I just cant figure how how the process starts. How do the particles get into the accelerator to start the experiment?

2007-06-26 01:19:15 · 4 answers · asked by Jason D 1

also applications of cones, 3d objects and vector quantities. plzzz help. last date 28 june

2007-06-26 00:48:07 · 7 answers · asked by Princess 1

I have been flying since before I was born (litterally). I go to Germany every year to see my family, but this year I have a son of my own. I have never before even thought twice about flying, but I am now terrified of it. All I can imagine is going down and looking into my sons face. Hes just confused and doesnt know hes about to die, and its all my fault because I put him on this plane.
Anyway, my question is, would you die before the plane goes into the ocean? (since we are over the atlantic for hours) Or would the impact kill you? Or wouldyou have to drown in the freezing water?
If it werent for these damned terrorists I also wouldnt have to be so scared because a wreck due to a planes physical defaults is extremely unlikely.

2007-06-26 00:46:16 · 13 answers · asked by Chrissy WB 2

ok so i pluck the string on my bass, and i watch it vibrate, its a sharp fuzzy blur that i see. now when i pluck the string and the tv is behind it in my line of vision, the string has a slower vibration movement and i can see the string waving.
like this pic, if that makes sense http://www.karbosguide.com/books/videosound/sound_files/image003.gif

my question is why can i see this in front of a tv or computer monitor?

2007-06-26 00:40:52 · 4 answers · asked by ? 3

2007-06-26 00:12:27 · 6 answers · asked by undine 2

An athelete swims a length of 50 m in a pool in 20 seconds.
and make his return trip to the starting position in 22 seconds.
detemaine his average velocity:
1.first half of the swim
2.second half of the swim
3.round the trip.
kindly solve it and explain

2007-06-26 00:07:24 · 6 answers · asked by Anonymous

(1) A 36 kg object is placed on a table. How much force is required to be applied on the object so that is moves with "acceleration" 15 m/s2.

(2) A particle starts from rest and moves with uniform acceleration. It moves a distance of 91 feet in the 7th second.Find its acceleration.

2007-06-25 23:54:14 · 3 answers · asked by Anonymous

2007-06-25 23:46:23 · 9 answers · asked by Quickfix008(∞Cicci∞) 5

can three vectors of equal magnitude be combined to give a zero resultant? How about three vectors of unequal magnitudes? kindly explain

tnx again! :)

2007-06-25 23:40:50 · 5 answers · asked by asker guy 2

can u give me full details?

2007-06-25 23:39:49 · 4 answers · asked by tejasvi_adiga 1

the law of conservation of energy states that energy cannot be created or destroyed, so where does all the energy come from?

2007-06-25 23:30:34 · 7 answers · asked by vyrill21 3

well sorry for my easy question, i am really a beginner and slow when it comes to problem solving

2007-06-25 23:17:57 · 6 answers · asked by Regine Yu 2

2007-06-25 23:11:28 · 8 answers · asked by undine 2

2007-06-25 20:29:24 · 7 answers · asked by Lee Edward 1

2007-06-25 20:18:12 · 7 answers · asked by Lee Edward 1

kymograph

2007-06-25 19:33:59 · 2 answers · asked by riemill 1

or at least some of them?

1. A bicyclist averages 18.0 km/hr for 20 minutes. What distance did the bicyclist travel?

2. What is the final velocity of a car that accelerates from rest at 9 ft/sec^2 for 8.0 seconds?

3. A sports car traveling 88ft/sec comes to a complete stop in a distance of 100 feet. a) How much time was required for the stop? b) What was the average deceleration.

4. A ball thrown stright yp reaches its highest point in 2.6 seconds. What was its initial velocity? Neglect air resistance.

5. You drop a rock from a cliff and it hits the ground 5.2 seconds later. How high is this cliff?

6. How long much a car accelerate at 4 m/sec^2 to go from 12 m/sec to 36m/sec?

7. An object is dropped from a bridge and hits the water 2.5 seconds later. a) with what velocity did it strike the water? b) What was its average velocity during the fall? c) How high is the bridge?

2007-06-25 18:55:04 · 3 answers · asked by YeonCouture 2

For example would a sound at 15,000 HZ travel faster than a sound at 60hz?

2007-06-25 16:57:25 · 7 answers · asked by Jeff B 2

I guess, in quantumelectrodynamics, there are probabilities for a photon to have velocities higher or lower than c, when measuring over very short distances. What does happen to the relativity stuff then?

2007-06-25 16:42:30 · 8 answers · asked by Anonymous

A 100 candle and a 64 candle source are 2m apart. At what point between them will the illuminance be the same?

2007-06-25 16:10:26 · 4 answers · asked by Kresnik 2

2007-06-25 16:01:47 · 6 answers · asked by garfieldrules2001 1

2007-06-25 15:53:02 · 6 answers · asked by westsideslider1979 1

A uniform diving board, of length 5.0 m and mass 54 kg, is supported at two points; one support is located 3.4 m from the end of the board and the second is at 4.6 m from the end (see the figure below). What are the forces acting on the board due to the two supports when a diver of mass 62 kg stands at the end of the board over the water? Assume that these forces are vertical. [Hint: In this problem, consider using two different torque equations about different rotation axes. This may help you determine the directions of the two forces.]

2007-06-25 15:45:16 · 1 answers · asked by Anonymous

a train goes forward at a speed of 1 m/s for 20 sec.then it stopsand goes backwards at a speed of 0.5 m/s for 4 seconds.after both movements are completed. howfar is the train located from its starting point. (only asking for the trains final location,not the total distancethat it travled) my answer was 19 ? other possible answers are 18 m
20 m 22m

2007-06-25 15:39:32 · 4 answers · asked by treasure 2

Carole's hair grows with an average speed of 3.5 x 0.00000001 m/s. How long in years does it take her hair to grow 0.30 m?

2007-06-25 15:24:25 · 2 answers · asked by Tam 1

When the emergency warning siren at Cheryl's school was tested, the sound from the siren took 7.0 s to reach her house located 2.40 km from the school. What is the speed of sound in air ?

2007-06-25 15:16:16 · 8 answers · asked by Tam 1