InovFX Posted November 27, 2004 Share Posted November 27, 2004 Hi, I'm new in here. I'm only 13 years old. I have a question : There are two car in a road. The first car run with speed 600 km/hour. And the second car run with speed 20 km/hour. How the first car look the second car ? How the second car look the first car ? Why ? Sorry if my english not good.... Link to comment Share on other sites More sharing options...
Ophiolite Posted November 27, 2004 Share Posted November 27, 2004 Apa kabar saudara InovFX, can you be more specific. Are the cars travelling towards each other, or in the same direction? When you ask 'how do they look to each other' are you thinking about the effects of relativity on their apparent lengths, or something else? Link to comment Share on other sites More sharing options...
InovFX Posted November 27, 2004 Author Share Posted November 27, 2004 The cars are travelling towards each other. Link to comment Share on other sites More sharing options...
cyeokpeng Posted November 27, 2004 Share Posted November 27, 2004 Assume that the cars are travelling towards each other at your stated speed, both speed are stated measured with respect to the Earth. The Gamma factor for SP is sqrt(1-v^2/c^2) is so close to unity that the effects of SP is very unobservable. Even if you add up the velocity according to Lorentz addition of velocity = (v(ba)-v(ca))/(1-v(ba)v(ca)/c^2), the addition is very close to the answer by adding v(ba) and -v(ca), due to the speed involved not at least 0.2 times the speed of light. At such low speeds, the effect of special relativity cannot be observed! Link to comment Share on other sites More sharing options...
maverick88 Posted November 27, 2004 Share Posted November 27, 2004 lol I think he asked about the velocitiy of rach car relatively to other Link to comment Share on other sites More sharing options...
timo Posted November 27, 2004 Share Posted November 27, 2004 >> How the second car look the first car ? The driver of car 2 would look at the first car with condused disbelief because he never saw a car doing 600 km/h before, I think. But that´s only if he even recognizes what kind of object just speeded by. Now seriously: They both would see the other one coming towards them with a speed of 620 km/h. Link to comment Share on other sites More sharing options...
[Tycho?] Posted November 27, 2004 Share Posted November 27, 2004 I'm not really sure whats being asked. They would look like very fast moving cars. Link to comment Share on other sites More sharing options...
InovFX Posted November 28, 2004 Author Share Posted November 28, 2004 Sorry, that question is wrong, and here the correct question : Look at this picture : The car 1 run with v=1km/sec and the car 2 run with v=1m/sec. Can the car 1 see the car 2 ? Can the car 2 see the car 1 ? How and why ? Link to comment Share on other sites More sharing options...
cyeokpeng Posted November 28, 2004 Share Posted November 28, 2004 Sorry, I didn't see your cars. Do most of you see it??? Link to comment Share on other sites More sharing options...
Jordan14 Posted November 28, 2004 Share Posted November 28, 2004 I didn't either Link to comment Share on other sites More sharing options...
timo Posted November 28, 2004 Share Posted November 28, 2004 Sorry' date=' that question is wrong, and here the correct question : Look at this picture : http://www.freewebs.com/freeways/v.gif The car 1 run with v=1km/sec and the car 2 run with v=1m/sec. Can the car 1 see the car 2 ? Can the car 2 see the car 1 ? How and why ?[/quote'] Not sure if I really understand what you are asking for but: - No the cars can´t see each other. At least I haven´t heard of any car being able to see. - The drivers of the cars can see (assuming they do have eyes) the other car if light from that car falls on their eyes. For example if sunlight is reflected on the car. - both drivers still percieve the other one as moving with 1001 m/s relative to them, respectively. I´m actually not sure if you wanted to create an example that needs relativity or not. If you wanted to make an example using (special) relativity you have to choose speeds roughly that of the speed of light (300000 km/s). With these "slow" speeds (1 km/s of course is very much for a car) there is not really a need to use relativity. EDIT: Perhaps it would be a good idea to explain what your thoughts on your problem are. It would help others to understand what your point is. Link to comment Share on other sites More sharing options...
InovFX Posted November 29, 2004 Author Share Posted November 29, 2004 I change my question again.. Look at this picture below : The Man 2 running around point x with velocity 300.000km/s (lightspeed). Can man 1 see the man 2 ? Can the man 2 see the man 1 ? I think the man 1 can't see the man 2 because he running very fast. But can the man 2 see the man 1 ? Link to comment Share on other sites More sharing options...
TrueHeart Posted November 29, 2004 Share Posted November 29, 2004 In this world of ours, there is no such thing as a physical object moving at lightspeed; it has been proven to be impossible -- it could never happen. Everyone can see everyone else... there are NO exceptions! Link to comment Share on other sites More sharing options...
YT2095 Posted November 29, 2004 Share Posted November 29, 2004 are you trying to ask about Red Shift or something? that`s one of the things your last diag could be used for in a question (I`m only guessing). and as above, lightspeed for an object wouldn`t be possible, and therefore neither is answering it. Link to comment Share on other sites More sharing options...
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