Question for the maths able..
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Deleted member 26715
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The cars them selves will still only be travelling at .6 no matter what direction they are going in
Alan...
Alan...
But is the speed the gap opens between them 1.2 the speed of light. If they were converging I guess the closing speed would be, so does the same rule apply if they are going in opposite directions. I don't know if the original question is a trick question.
Alien8
Senior Moment
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Yes it would - but it would be red-shifted.
In more technical language than you may care for in 'Newtonian Mechanics' the frames of references have Galilean Transformations. This means you can add up the 'relative motions' to be whatever you want.
Special Relativity uses something called Lorentz transformations (which was actually around before SR as we know it today, it's just that it was a slight puzzle) where the speed of light cannot be exceeded. Consequences are that a reference frame for different observers may be completely different.
The confusion really arises because the Newtonian is an approximation to SR for low speeds.
The term that mucks it up is called the Lorentz factor. The terms for the two do look not totally dissimilar for the two types of transformations (there are many variants). Instead of x' = x -vt you end up with a γ term in front x' = γ(x-vt) and for time things are a bit more complicated, but not much. The idea being that between the two objects under Galilean transformations the distance/displacement will be different by vt i.e. speed x time = a distance if you're wondering where it comes from. In other words what you'd 'expect'.
And the reasoning for mentioning the names is that you may find it instructive to look them up and find out more.
Alien8
Senior Moment
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- (A little bit north of) Cambridge
This distance between the cars would be increasing at 1.2 times the speed-of-light m/s. But if either car were to measure the other car's velocity they would still get 0.6 times the speed-of-light m/s because velocity is with respect to an inertial reference frame.
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Fnaar
Smutmaster General
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What colour are the cars?
Dunno but I'm guessing the gear levers are red shifters.
Fnaar
Smutmaster General
- Location
- Thumberland
If they were on opposite facing treadmills, and had wings...
So is that a yes?
Alan...
They travel apart at 0.88c.
However I find that people ask these questions on forums and everyday life all the time. You can just say how it is to which they might just carry on thinking the same as they always did or they might think ah it's not like that. But some people would say they aren't that likely to understand. On the other hand that doesn't mean that anyone who has studied it at whatever level necessarily explains it well or to the liking of the person asking. But it's worth a try.
I suppose you could then talk about what is generally referred to as the Michelson-Morley experiment in popular science books. There have been many such experiments conducted in the 19th and 20th centuries. There is no aether. So you could measure the speed of light taking into account the earth moving around the sun or galactic centre or whatever. Or even get onto more modern experiments. I suppose you could even mention GLAST, ph here.
So which is it, the Lorentz Factor or the X factor?
I've found this explanantion on the internet which explains it in simpler terms than marinyork
http://www.clays.org/journal/archive/volume 34/34-4-359.pdf
Well time certainly does seem to slow down for the observer during X-factor.
02GF74
Über Member
let's say both drivers put their foot down so each car is travelling a 1.0c.
an observer would see each car travelling at 1.0c - the driver of one car would see the other car moving away from him/her again at 1.0c (assume they are travelling in oppiste directions) and this is where it gets confusing coz you'd think it will be 2.0c but for relativity stuff - someone want to explain that in simple terms?
an observer would see each car travelling at 1.0c - the driver of one car would see the other car moving away from him/her again at 1.0c (assume they are travelling in oppiste directions) and this is where it gets confusing coz you'd think it will be 2.0c but for relativity stuff - someone want to explain that in simple terms?
