English_Wolf Loc: Near Pensacola, FL

A man runs to catch a train, jumps into the last wagon. He then has to walk to the head of the train to find his seat, what speed did he travel at when the train arrives at destination to a complete stop?

From there, if someone fires a laser inside a train from the back of the train to the front, what speed did the light travel at when the train stops?
If the laser is fired from the front to the rear, what speed did the light travel at when the train stops?

If seen from the outside, as the man walks to his seat, what was the speed of the man? Then, what was the speed of the light (in both direction)?*

This is where I start having problems with Einstein... (remember, I hate math)

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*Relative to the observer.

Nikon_DonB Loc: Chicago

I hate to say it Wolfie but I believe you have been reading too many of Diet's posts.

Just FYI, the speed of the laser(light) is 186,000 miles per second. Or for you metric fans it's roughly 299,000,000 meters per second. That's in a vacuum, of course. In air it's .026% slower.

See what you started! LOL. Good Post!

professorwheeze Loc: Maine, USA

The average boxcar is about 25 meters. So in one-second the train would have to be about 1,200,000 cars. A caboose every 100 cars. So 12,000 red cabooses. That's a picture I would submit to the "Red Thread".! Guess I have too much break time. Back to work!

tschmath Loc: Los Angeles

According to the theory of relativity, the speed of the laser as well as the speed of the person moving on the train is different on the train than to an observer on the ground. Infinitesmally different, but different nonetheless. Time is different, too, but that another whole mind blower.

English_Wolf Loc: Near Pensacola, FL

That is not my question....

BigBear Loc: Northern CT

Too many missing variables to conclude an answer.
However, if you were to fill in the variables with, just for kicks, PI ...

Just because I like pie. :P

English_Wolf Loc: Near Pensacola, FL

First question is rather simple, it has to do with distance traveled inside and within the train.

snowbear

Since no speeds (other than the constant speed of light) were not defined:

From inside the train, the man appears to move at his normal walking speed. To an observer outside the train he appears to move at his normal walking speed plus the speed of the train.

The speed of light is the same from both a stationary and a moving source, so the apparent speed of the laser beam would be the same by observers on the train, as well as those outside the train.

English_Wolf Loc: Near Pensacola, FL

But the question is what speed did he travel at when the train is at a full stop.

ngc1514 Loc: Atlanta, Ga., Lancaster, Oh. and Stuart, Fl.

Since the man and train left the departure point and arrived at the destination at the same time, his average speed was the same as the train.

As Snowbear pointed out, the speed of light in a vacuum is constant for ALL observers. If you on a space ship traveling at 99% the speed of light, you will measure the speed of a light ray traveling in the same or opposite direction to your line of travel as 186,284 miles per second.

The answer to the old question of what happens if you are in a car traveling at 99.9999% the speed of light and you turn on the headlights is... It will not make any difference to the speed of light whether you are in motion or parked in your driveway.

sudzmonn Loc: here , there , everywhere

188,000 miles per second

snowbear

Assuming he was seated when the train arrived, he would be traveling at zero.

Unless he was observed by the aliens in space, at which point he would be moving at the speed of the earth around the sun, as well as in rotation about its axis, but this is another story. :D

English_Wolf Loc: Near Pensacola, FL

The question is:
what speed did he travel at when the train arrives at destination to a complete stop?
It is simple, there no trick not alien no nothing.
The answer is also simple.
To make simpler...
If the train is 1 mile long and the train stopped 100 miles from the point of departure. When the train stops, the man has effectively traveled 101 miles.
The speed is the distance / time.
Still to keep it simple and say the time was one hour (European/Japanese high speed train) the man has traveled at 101 mph while the train traveled at 100 mph).
Now my problem with Einstein (as if) is that he does take into account the possibility to stop light. This has been achieved a few years ago for about 2/100th of a second. If you take this into account you quickly realize that something is wrong somewhere. I asked friends at the CNRS and none has an answer when it came to stopping and storing light THEN calculate the speed.

So, yeah, brain teaser that has absolutely no meaning other than entertainment for the masses.

http://www.news.harvard.edu/gazette/2001/01.24/01-stoplight.html

If you can stop it and store it inside a moving object once arrived at it destination the speed is additional so...

nikon_jon Loc: Northeast Arkansas

I thought about your conundrum but not too hard because I have no math skills and I certainly am no Herbert Einstein, or whoever that guy was. But I do know what a conundrum is. Words are my thing.

dasboat Loc: Vernonia,Ore.(Vernowhere)

The speed of light never changed at any time.