How fast does light travel in 1 ft?

[dan001]

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.

 

[cesiumfrog]

speed = distance / time. Use google calculator. Welcome to PF.

 

[Gokul43201]

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]

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]

How much time to cover 300,000,000 meters (that's about 1,000,000,000 ft)?

um... wait, gimme just a ...

 

[neutrino]

gimme just a ...

...and a teeny, tiny bit more.

 

[mgb_phys]

Light travels at 1 foot / atto-fortnight, everyone knows that.

 

[Feldoh]

Light travels at 1 foot / atto-fortnight, everyone knows that.

You are a nerd among nerds

 

[mgb_phys]

No, a real nerd uses c = 1.8 terafurlongs per fortnight

 

[HallsofIvy]

No, a real nerd uses c = 1.8 terafurlongs per fortnight

And watch them ponys run!

 

[Dick]

No, a real nerd uses c = 1.8 terafurlongs per fortnight

Um, what's that in Planck units?

 

[mgb_phys]

That would be a good homework question, what is Planck's constant in the furlong/firkin/fortnight system.

 

[Dick]

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?

 

[robphy]

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^3 .
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+firkin*(1000+kg/m^3)

So, since google has a problem with numerical constants in the unit conversion,
http://www.google.com/search?q=h/1000+in+(firkin)*(kg/m^3)*furlong^2/fortnight

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+furlongs+per+fortnight yields
the speed of light = 1.8026175 × 10^12 furlongs per fortnight)

 

[mgb_phys]

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_strange_units_of_measurement