How fast does light travel in 1 ft?


by dan001
Tags: light, travel
dan001
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#1
Aug7-07, 11:26 PM
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Hello everyone,

I was wondering if anyone could help solve my problem...

...How much time in seconds (or milleseconds) would light travel in 1ft? (assuming that it was traveling in a vacuum.)

I spent 2 and a half hours yesterday trying to solve this problem, but without much luck. I remember back in school, I would know how to do this kind of stuff, but now...well, you know.

If anyone knows the answer to this problem (and if possible, a formula), I would much apreciate it.
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cesiumfrog
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Aug7-07, 11:31 PM
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speed = distance / time. Use google calculator. Welcome to PF.
Gokul43201
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Aug7-07, 11:55 PM
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How much time to cover 300,000,000 meters (that's about 1,000,000,000 ft)? So, how much time to cover 1 ft?

dan001
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#4
Aug8-07, 12:12 AM
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How fast does light travel in 1 ft?


Quote Quote by cesiumfrog View Post
speed = distance / time. Use google calculator. Welcome to PF.

Wow, I don't believe how I could forget something so simple.

Thanks anyways for reminding me.
robphy
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Aug8-07, 07:34 AM
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Quote Quote by Gokul43201 View Post
How much time to cover 300,000,000 meters (that's about 1,000,000,000 ft)?
um... wait, gimme just a ....
neutrino
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#6
Aug8-07, 08:14 AM
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Quote Quote by robphy View Post
gimme just a ....
...and a teeny, tiny bit more.
mgb_phys
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Aug8-07, 09:01 AM
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Light travels at 1 foot / atto-fortnight, everyone knows that.
Feldoh
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Aug8-07, 03:50 PM
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Quote Quote by mgb_phys View Post
Light travels at 1 foot / atto-fortnight, everyone knows that.
You are a nerd among nerds
mgb_phys
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Aug8-07, 04:58 PM
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No, a real nerd uses c = 1.8 terafurlongs per fortnight
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Aug8-07, 07:03 PM
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Quote Quote by mgb_phys View Post
No, a real nerd uses c = 1.8 terafurlongs per fortnight
And watch them ponys run!
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Aug8-07, 11:21 PM
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Quote Quote by mgb_phys View Post
No, a real nerd uses c = 1.8 terafurlongs per fortnight
Um, what's that in planck units?
mgb_phys
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Aug8-07, 11:24 PM
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That would be a good homework question, what is planck's constant in the furlong/firkin/fortnight system.
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Aug8-07, 11:34 PM
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Quote Quote by mgb_phys View Post
That would be a good homework question, what is planck's constant in the furlong/firkin/fortnight system.
Mines a trick question. In planck units c=1, hbar=1 and G=1. Yours is harder. What's the mass unit in the firkin system? Stones, right?
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Aug9-07, 12:29 AM
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Quote Quote by mgb_phys View Post
That would be a good homework question, what is planck's constant in the furlong/firkin/fortnight system.
Using dimensional analysis,
h is in Joule-seconds or kg*(m/s)^2*s = kg*m^2/s

Although http://en.wikipedia.org/wiki/FFF_System says that firkin is a mass,
according to http://en.wikipedia.org/wiki/Firkin and google, firkin is a volume: http://www.google.com/search?q=firkin+in+m%5E3 .
However, since it is used with water (whose density is about 1000 kg/m^3), we have an expression for the mass in kg of a firkin of water http://www.google.com/search?q=kg+in...+kg%2Fm%5E3%29

So, since google has a problem with numerical constants in the unit conversion,
http://www.google.com/search?q=h%2F1...E2%2Ffortnight

h / 1 000 = 4.8405995 × 10-34 (firkin * (kg / (m^3)) * (furlong^2)) / fortnight


or
h = 4.8405995 × 10^(-34) (firkin of water) * (furlong^2) / fortnight


(FYI: http://www.google.com/search?q=c+in+...+per+fortnight yields
the speed of light = 1.8026175 × 10^12 furlongs per fortnight)
mgb_phys
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Aug9-07, 09:21 AM
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Well done, although a traditionalist would say that mass should be a firkin of ale not water!

Some interesting units I hadn't heard of here http://en.wikipedia.org/wiki/List_of...of_measurement


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