Physics Conundrum.

[Dork Lard]

On the basis that there's some very clever folk who live in these parts . . . .

Qu. You have a 6ft long solid bar connected at one end to a lightswitch. When you push the other end it operates the lightswitch & the light comes on. If the solid bar was 5,878,625,370,000 miles long, how long would it take for the light to come on?

No prizes & Google is not your friend.

 

[Munroast]

the light would come on immediately but you wouldn't see it for a year

 

[Dork Lard]

the light would come on immediately but you wouldn't see it for a year

Sorry, but it's not that easy.

 

[RandomGrinch]

the light would come on immediately but you wouldn't see it for a year

That's assuming an 'infinitely rigid' bar - given the mass of the bar, any press we made would create an equal and opposite reaction. The switch wouldn't move, we would push ourselves backwards!

 

[conny]

How far away from the switch is the light source? (At the other end of the solid bar, maybe?)
Basically we do not have enough information to correctly answer the question.

 

[Dork Lard]

That's assuming an 'infinitely rigid' bar - given the mass of the bar, any press we made would create an equal and opposite reaction. The switch wouldn't move, we would push ourselves backwards!

I knew there'd be at least one. Try to imagine that this is not a bar that you can buy in Screwfix. It is 5,878,625,370,000 miles long & it is rigid, they are the only criteria specified.

 

[Dork Lard]

How far away from the switch is the light source? (At the other end of the solid bar, maybe?)
Basically we do not have enough information to correctly answer the question.

Don't fret too much. When faced with a question they cannot answer many folk try to redefine the question.

 

[Trazor]

5,878,625,370,000 ÷ 186,0000 miles per second = number of seconds it will take.

Divide by 60 for minutes.

Divide by 60 for hours.

Divide by 24 for days, this equals 365 days, give or take. So 1 year.

 

[Dork Lard]

5,878,625,370,000 ÷ 186,0000 miles per second = number of seconds it will take.

Divide by 60 for minutes.

Divide by 60 for hours.

Divide by 24 for days, this equals 365 days, give or take. So 1 year.

When the light comes on it would take you 1 second to see the light.

This is a physics conundrum, 1 second is not the answer.

 

[Trazor]

When the light comes on it would take you 1 second to see the light.

To see the light in 1 second, the light would only be 186000 miles away.

Your light is 1 light year away, assuming the switch is next to the light.

 

[RandomGrinch]

It is 5,878,625,370,000 miles long & it is rigid

Infinitely rigid? If so, the atoms would be packed in so tightly that it would have an infinite mass, and would probably instantly disintegrate, probably destroying a little bit of the universe with it?

 

[IT Minion]

What's the speed of propagation of a solid bar? The bar won't be moving instantly over that distance, as that would violate the speed of light, solid or not it will take time for the movement to propagate.

It's a physics problem, but it's not a simple one

 

[Dork Lard]

Infinitely rigid? If so, the atoms would be packed in so tightly that it would have an infinite mass, and would probably instantly disintegrate, probably destroying a little bit of the universe with it?

Like I said, you can't buy one at Screwfix.

Let's just try to imagine that it is an infinitely rigid bar that weighs nothing. The point is that when you push one end the light comes on.

 

[Dork Lard]

What's the speed of propagation of a solid bar? The bar won't be moving instantly over that distance, as that would violate the speed of light, solid or not it will take time for the movement to propagate.

It's a physics problem, but it's not a simple one

Well, it seems there is intelligent life on DIYNOT.

Did you work it out for yourself or have you been asked the problem before?

 

[Old Salt]

Who cares, is this infinitely Bar open or not