Okay, so lets say that there is a train. One person is standing in the train, and another is outside looking in. The person in the train has a ball and a flashlight. We know that relative to the person standin on the ground, that the ball is traveling whatever speed the ball was thrown plus the speed of the train. We also know that if the person in the train turns on the flashlight, the light is still going 299,792,458 meters per second relative to the person on the ground. So, here is my question: Somehow, we get the train to go at half the speed of light. If the person on the train could somehow throw the ball at half the speed of light, wouldn't the ball be going AT the speed of light, and be breaking the laws of physics? If the ball COULD in fact go that fast, would IT itself BECOME light? Thoughts?
2006-10-16 11:43:38 · 12 answers · asked by aggies_2011 2 in Science & Mathematics ➔ Physics
The speed of the ball, as seen by the person in the train is:
v'ball = c/2
The speed of the train, as seen by the person by the side of the track, is:
vtrain = c/2
The problem you are having is you are still thinking of the ball in terms of non-relativistic mechanics (which works well for speed below, say, c/2):
vball = v'ball + vtrain = c
You forgot to take into account the relativistic correction. The speed of the ball, as seen by the person by the side of the track, is actually:
vball = (v'ball + vtrain) / [1 + (v'ball*vtrain)/c²]
= c / [1 + 1/4] = (4/5)c
Now use this equation to see what the person by the track would see as both v'ball and vtrain go toward c:
vball ──> (c + c) / [1 + (c²/c²)] = c
...and thus the universal speed limit is enforced...nothing can go faster than c...you saw this with the flashlight.
To answer your second question, if the "ball" COULD go as fast as the speed of light it would, in fact, have to BE light...as in nothing with mass can go as fast as light (but no, nothing magical happens as something with mass speeds up close to the speed of light). This has to do with the energy required to accelerate a particle with mass: as the speed increases to c, the energy required to accelerate the particel increases to ∞.
2006-10-16 12:21:58 · answer #1 · answered by Anonymous · 0⤊ 0⤋
You information was incorrect about all energy having mass. Radiation, or light waves contain no mass. Some people argue that it has an 'effective mass' given by some of the E=hf (engery=plank's constant times the frequency), but that's still debated. Reguardless, light has no mass, and that's why it can travel @ the speed of light c. You are correct about accelerating a partlice towards the speed of light would require infinite amount of energy. If you're really intrested look @ Lorentz transformations, and you can see the fairly easy why anything with mass can not reach the speed of light.
2016-03-28 12:06:34 · answer #2 · answered by Anonymous · 0⤊ 0⤋
In a train at half the speed of light, time and distance are changed and the guy on the train sees the light moving away from him at exactly the speed of light. But to a stationary observer looking at the train speed by, the light beam is only pulling ahead of the flashlight at half the speed of light, because time and distance are not altered for him.
2006-10-16 11:54:23 · answer #3 · answered by campbelp2002 7 · 1⤊ 0⤋
No, it will not travel at the speeed of light. You forgot to take relativistic effects into consideration.
It is impossible to accelerate ANY object with mass -- even just an electron -- to the speed of light. To do so would take an infinite amount of energy.
2006-10-16 11:52:39 · answer #4 · answered by poorcocoboiboi 6 · 0⤊ 0⤋
There is, in relativistic mechanics, a rule for addition of velocities which is different than the simple Newtonian addition rule. It is, if I remember correctly:
Vtot = (V1 + V2)/sqrt(1 - V1 V2/c^2).
Thus the sum of two velocities will always be less than the speed of light.
2006-10-16 11:48:50 · answer #5 · answered by Anonymous · 3⤊ 0⤋
if u use pythagorean theorem, the speed of the ball is only half the speed of light times the sqrt of two, so your ball isnt at speed of light yet
2006-10-16 11:47:13 · answer #6 · answered by ? 2 · 1⤊ 0⤋
anything traveling at the speed of light would in fact turn into light
2006-10-16 11:53:57 · answer #7 · answered by Moneymike 3 · 0⤊ 0⤋
first we gotta get that train going half speed of light right? Allow me to quote Einstein here "in an infinite universe, there are infinite possibilities"
2006-10-16 11:46:44 · answer #8 · answered by Smitten_Kitten 4 · 0⤊ 1⤋
wow...this is a good one.....in all reality...and logic...yes this is correct....as for the ball becoming light itself is impossible to say because the only thing thats ever gone at lightspeed is light itself...i hope i helped
2006-10-16 11:47:23 · answer #9 · answered by norm n 2 · 0⤊ 2⤋
well, no. if something travels the speed of sound, does it become sound? of course not.
2006-10-16 11:47:43 · answer #10 · answered by Anonymous · 1⤊ 0⤋