Constant speed of light (2 Viewers)

[Xayma]

They trick you so that they can make a calculation worth more marks but not involve any hard maths.

 

[abdooooo!!!]

yeah... they have excuses like this is not math its physics. hahaha

 

[Xayma]

That question is as much testing your english skills as it is your maths skills. Trickssy board of studiessess

 

[abdooooo!!!]

hahaha... im remembering something... ahh... can't... i remember reading something about how easy but tricky hsc science is. now thats so true.

 

[Wohzazz]

LOL, yeah i realised it was radius and did it 'my way' subing in the diameter which doesn't make sense but equates to the same asnwer. I guess it was the fact that the speed of the craft was so close to the speed of light that it didn't affect the calculation. But thanks, now i see why my cal didn't make sense.

BTW why do they introduce parsec. Can't they stick with light years and astronomical unit. Do you need to remember these conversions?

By the way, for the time dilation thingy, i getting a lil confused.
Say that we have some tunnel that is 80m long. If you travel near the speed of light in a 120m train, your train gets contracted to a length that will fit in the tunnel from an onlooker outside's frame of reference. Does this length contraction last if after your train goes to a sudden halt? no?
And for the person inside, wouldn't they see the tunnel shrink? So then they don't see their train fitting yes?

edit/ Can you completely delete a post? i realised i posted it twice when the forums were laggy

 

[Xayma]

Parsecs are useful for determining the distance to stars via parallax, it makes it a whole lot easier to calculate distances then trying to do light years.

 

[Wohzazz]

Originally posted by Xayma
Parsecs are useful for determining the distance to stars via parallax, it makes it a whole lot easier to calculate distances then trying to do light years.

another thing i don't know, why do i bother asking?!

 

[Xayma]

Don't worry about it you dont need to know it until/if you do astrophysics.

 

[abdooooo!!!]

yes... see when the train comes to a sudden halt... i suspect the passegers and the train would just dissipate into little tinny ions or subatomic particles and fly away...

edit: so you'll weren't see anything at all... but might get struck by red hot particles.

 

[Wohzazz]

Haha, were you being serious....so how about if you accelerate something to say 0.9c, then gradually decelerate it...will it return to its original size

 

[Xayma]

Actually the train will still probably fit in the trouble because the kinetic energy when it stops will partially be used to deform the train, and thats alot of kinetic energy to get rid of. Plus you will turn a whole lot into plasma.

 

[Wohzazz]

Ok, how about consider this damn train to be indestructible to deformation due to kinetic energy (hypothetically). Does it return to its original shape?

 

[abdooooo!!!]

why not? if you're the same speed as the train then you should see the train at the same length... have any scientist actually tried doing that? hahaha make a indestructable train.

 

[Xayma]

Well it only left its original shape relative to the observer, so it never really left it.

Energy can neither be created nor destroyed, so if it didnt go into deforming the train most likely it would of went into heat, so you would have been fried anyway.

Why would a scientist try to make an indestructible train, that's an engineer's job.

 

[Wohzazz]

Originally posted by Xayma

Energy can neither be created nor destroyed, so if it didnt go into deforming the train most likely it would of went into heat, so you would have been fried anyway.

Got hammered again.:mad1:

What happens if you hypothetically, block boths ends of the tunnel at the particular point the train is in it accelerated near the speed of light(so it is contracted relative to the frame with the tunnel). Please note that the tunnel is 80m, and train is 120, which wouldn't fit normally.

 

[abdooooo!!!]

Originally posted by Xayma
Energy can neither be created nor destroyed, so if it didnt go into deforming the train most likely it would of went into heat, so you would have been fried anyway.

quoting from the first law of thermodynamics: the change in internal energy of a system is equal to the heat added to the system minus the work done by the system.

but what happen if the train is heat proof... full proof.

Originally posted by Xayma
Why would a scientist try to make an indestructible train, that's an engineer's job.

nah thats what science engineers are for... is there such a thing?

edit: you still can't see it... too much flames around... it'll be like the sun train.

 

[Xayma]

How can you have a heat proof train? You could have one with a specific heat --> infinite but still its a form of electromagnetic energy.

 

[abdooooo!!!]

Originally posted by Wohzazz
What happens if you hypothetically, block boths ends of the tunnel at the particular point the train is in it accelerated near the speed of light(so it is contracted relative to the frame with the tunnel). Please note that the tunnel is 80m, and train is 120, which wouldn't fit normally.

what are you? E albert? are you trying to propose some sought of thought experiment which could lead you to a noble prize?

seriously how would you know? no one knows for sure... you can just make crap up...

 

[Constip8edSkunk]

there will be a pretty big crash

 

[Xayma]

How could you block both ends of the tunnel when it will spend only 6 2/3 x10^-7 seconds in the tunnel?