I have a question regarding freight train speeds. Explanation:

>>8017946
There is no way to answer that. You're only giving a mass of the train and saying that it moves at a constant speed. Nothing can be done with that information.

>>8017950
I can confirm this, if it helps; it goes faster than 40km/h but no faster than 100km/h

>>8017951
Cool, man. You only put a restriction on the answer, not added any info in order to find the answer. What you need is a measure of the train's momentum or kinetic energy.

>>8017951
40<v<100

If you want a better answer than that, you are just going to have to either measure the speed (like with a speed gun), or measure the time it takes to travel a measured distance.

>>8017959
It takes 27 seconds for a train to pass my window, which is 230cm.

>>8017966
Now that's something. How far is your window from the tracks?

150 meters

>>8017970
And how far are you from your window when you look at the train passing through it?

>>8017972
65cm, my desk in front of me.

>OP replying to his own thread to ask the correct questions instead of putting all the info in his original post

Good work buddy

>>8017977
I'm no maths major, it's not like I know all the info to provide. I thought the weight was enough, though the 27 sec thing was originally meant to be in the post.

File: starting point.png (19KB, 800x600px) Image search: [Google]

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>>8017984
Working from your information, we know that a whole train traverses the 270cm of the window in 27 seconds. Now we have to translate that to the real distance it traverses in that time, and we can do so with pic related.
L is the real distance on the tracks.
D is the distance from your house to the tracks.
Alpha is the angle of your sight.
H is the hypotenuse of the triangle of half your sight.
It is quite easy to see that (L/2) = H * sin(alpha/2).
Next we have to get alpha.

File: getting alpha.png (62KB, 800x600px) Image search: [Google]

62KB, 800x600px

>>8017997
Getting alpha is trivial when we get info from your desk and your window. Again, in here, we have to get H to work our way through alpha. Of course, with Pythagoras' theorem, we see that H2 = 0.652 + 1.352

>>8017997

Nice assumptions friend

>>8017946
Just go out at night with a stopwatch. Beforehand mark off 100 meter stretch. Stand at the end of that stretch with your stopwatch. When the train enters your 100 meter zone start your stop watch and stop it once it hits the end of your 100m zone. Then use the old d=rt formula to calculate it's speed/rate.

>>8017999
>H2 = 0.652 + 1.352
Meant to say H^2 = 0.65^2 + 1.35^2

Once you have gotten L from the first picture, it should be much easier.