Brain Teasers
Light Train
Science
Science brain teasers require understanding of the physical or biological world and the laws that govern it.Science
You're on a train. The train is moving at half the speed of light, or 93,000 mps (miles per second). You turn on a flashlight.
Question: How fast is the light travelling relative to the observer standing alongside the tracks?
a. 93,000 mps
b. 186,000 mps
c. 279,000 mps
Question: How fast is the light travelling relative to the observer standing alongside the tracks?
a. 93,000 mps
b. 186,000 mps
c. 279,000 mps
Answer
186,000 mpsThat's right! Relative to the observer, the light is moving at 186,000 mps. Seems non-commonsensical, doesn't it? But this has proven to be true through many experiments over the years.
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Comments
All I want to know it, where does one catch this train and where in the heck are they going?
I would stand along the side of any track that has an object traveling at half the speed of light. The wind blast alone would kill you.
I slept throught most of my physics classes at uni but I still remember them telling me the speed of light is constant and does not conform with the theory of relativity. eg, A is correct.
Apr 28, 2002
check Eistein theory .... I think light is constant, at the speed of light Newtonian theory fails, Eisteins theory of relativity compensates this.
Aug 14, 2002
I sense much debate. Build a train you must. Take a flashlight you will. Speed of light is constant, as far as us simple humans know.
The entire of Einstein's theory of special relativity is based on the fact that the speed of light is measured to be the same for all observers, no matter what their velocity is relative to everything else.
How would this work? I don't know if I can even understand the things the way they are currently stated, let alone when you say this. What about things like Doppler shift? time/gravity dialation? I don't see how it would work without creating some stitch in time or a weird mirrored singularity thing. Ah, I don't know what I'm saying. Time for a grilled cheese sandwhich!
Bleh, never mind. Read it wrong. Maybe I should skip the grilled cheese and get some R/R. Definitely! I'm thinking to myself R/R = Railroad. Look what you people are doing to me!
So what happens if there are 2 trains travelling at half the speed of light towards each other and a light is shone forwards from each train. At what speed are the light beams approaching each other?
acoording the the theory of relitivity LIGHTS SPEED IS THE ONLY CONSTANT.....great teaser
The speed of light is constant so the approach would be at 2x the speed of light. Nice problem...if you want to debate read einstein first!
Einstein added another constant to his equations (the name escapes me) to make the universe not expand. He then reneged on the concept. Then in the 1990's they found a use for it again.
hehe and if you figure VSL (variable speed of light) into your math, Einstein is wrong, and all that base their math on his work are, consequently, wrong! hahahahha
ttam007, I think the name that escapes you is the Cosmological Constant.
yetdjc15, just to nitpick: Einstein derived his theories of Relativity using The Principle of Invariant Light Speed as a postulate -- he essentially assumed it to be true (it was well-supported by emprical observation). Relativity itself is even stranger. :-)
yetdjc15, just to nitpick: Einstein derived his theories of Relativity using The Principle of Invariant Light Speed as a postulate -- he essentially assumed it to be true (it was well-supported by emprical observation). Relativity itself is even stranger. :-)
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