question (1 Viewer)

[Danger]

Two distant quasars A and B are on opposite sides of the earth and are moving away from us at 0.9c where c is the speed of light. At what speed will light from Quasar B hit:

a) earth
b) Quasar A
Justify your answer.

Please help, I do not get what this question is asking at all.

 

[Steth0scope]

The speed of light 'c' is constant in a vacuum at 3x10^8m/s. Therefore, no matter where, coming from whichever object, the speed of light is 3x10^8m/s.

I think?

 

[Forbidden.]

The speed of light 'c' is constant in a vacuum at 3x10^8m/s. Therefore, no matter where, coming from whichever object, the speed of light is 3x10^8m/s.

I think?

Yeah it's the assumption of special relativity, if space and length contracts and time dilates together then the speed of light must be a constant 3x10⁸ms^-1, regardless of the motion of the source or observer. v = s / t

 

[Danger]

Thanks

 

[wogblogger]

ohh somethin interestn that i liked was that
when there are objects that are traveling towards each other at relativistic speeds then you cant use vector addition to find the relative speed of one

the reasoning behind this is that say object 1 is travel'n at .8c and object 2 is travel'n at .7c (c being the speed of light) then with our knowladge from prelim course we wold say object 1 see's object 2 approching at 1.5c
but OMG that dosnt make sense bcuz its faster than C

soo what u do is use this formula (V1+V2)/{1+(V1V2/c^2)}

where V1=0.8c
and V2=0.7c

haha how cool is that

 

[kooltrainer]

pretty cool
































lol

 

[kony]

That's the Lorentz transformations, which are mentioned in the textbooks, but sadly are not in the syllabus, making relatvitiy questions extremely ambiguous and difficult to set.

 

[wogblogger]

kong is a genious
haha help me ....i dunno how just do it

 

[samwell]

congrats bro. U r a really smart kid. How the hell didnt u make any mistake in the three unit exam. Thats brilliant.

 

[samwell]

I saw the formula in Jacaranda Physics. Its really cool to use it in explanations.