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Old October 4th, 2010, 03:08 AM   #3461
SamuraiBlue
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Quote:
Originally Posted by chornedsnorkack View Post
1 m/s² acceleration is quite practical to handle on trains. Sustain it for 2 minutes and you are at 432 km/h (the speed of Transrapid), having covered 7200 m.
Hate to nag but you're missing 1/2 in your equation.



s = displacement
u = initial velocity
v = final velocity
a = uniform acceleration
t = time.
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Old October 4th, 2010, 08:51 AM   #3462
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Quote:
Originally Posted by SamuraiBlue View Post
Hate to nag but you're missing 1/2 in your equation.
I am not.
120 m/s*120 s /2=7200 m. As stated.
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Old October 4th, 2010, 12:49 PM   #3463
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Quote:
Originally Posted by chornedsnorkack View Post
I am not.
120 m/s*120 s /2=7200 m. As stated.
Your acceleration rate is 1m/s in a two minute time scale so you need to divided it by another 2 since your displacement of 7,200m is for 2 minutes not 1.

120^2/2/2/1000*60=216Km/h
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Old October 4th, 2010, 12:51 PM   #3464
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Quote:
Originally Posted by SamuraiBlue View Post
Hate to nag but you're missing 1/2 in your equation.



s = displacement
u = initial velocity
v = final velocity
a = uniform acceleration
t = time.
So why don't the blue Samurai take a WILD guess: how much is the initial velocity in chornedsnorkack's scenario?

So much for the usefulness of committing mechanically to memory high school physics formulae
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Old October 4th, 2010, 01:07 PM   #3465
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Quote:
Originally Posted by SamuraiBlue View Post
Your acceleration rate is 1m/s in a two minute time scale
Well, no acceleration has m/s as unit. That is, as philosophers' would say, a categorial mistake.

But I see you are talking about the speed at the end of two minutes, rather than the distance travelled.

For that, how about just multiplying time with acceleration

which is 120s x 1m/s/s = 120 m/s = 120x3.6 km/h = 432 km/h. Which part of it do you not understand, blue Samurai???

You need to understand the formulae you memorize and apply the right one.
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Old October 4th, 2010, 04:42 PM   #3466
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Okay, fellows, dig this.

Longest distance between two points on the surface of Earth is approximately 20.000 km (half Earth`s circumference).

Let`s assume we have a vactrain with only 0.5G acceleration - 5m/s^2. (This give us total G-force during travel equal to sqr(1^1+0.5^2)=1.118G. Piece of cake).

We need to accelerate 10.000km, then decelerate 10.000km. According to S=0.5*a*t^2:

10.000.000=2.5*t^2 ----> t=2000 second.

Our full journey is then T=4000 second or 66 minutes.

So the longest possible journey on such a vactrain will take a bit more than a hour.

Now tell me this isn`t a dream worth dreaming.
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Old October 4th, 2010, 06:44 PM   #3467
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Quote:
Originally Posted by Vanzetti View Post
Okay, fellows, dig this.

Longest distance between two points on the surface of Earth is approximately 20.000 km (half Earth`s circumference).

Let`s assume we have a vactrain with only 0.5G acceleration - 5m/s^2. (This give us total G-force during travel equal to sqr(1^1+0.5^2)=1.118G. Piece of cake).

We need to accelerate 10.000km, then decelerate 10.000km. According to S=0.5*a*t^2:

10.000.000=2.5*t^2 ----> t=2000 second.

Our full journey is then T=4000 second or 66 minutes.

So the longest possible journey on such a vactrain will take a bit more than a hour.

Now tell me this isn`t a dream worth dreaming.

Yeah, a piece of cake, except you can't have a piece of cake on board: you have to stay buckled tight for the journey to enjoy the hour-long deep massage of your internal organs, with the G-force and the Coriolis force working in two different directions Not only cakes, you'd have to forget about a on board too.

Which makes it so appropriate to call it the "sparta express"
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Old October 4th, 2010, 07:10 PM   #3468
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Quote:
Originally Posted by Ariel74 View Post
Yeah, a piece of cake, except you can't have a piece of cake on board: you have to stay buckled tight for the journey to enjoy the hour-long deep massage of your internal organs, with the G-force and the Coriolis force working in two different directions Not only cakes, you'd have to forget about a on board too.

Which makes it so appropriate to call it the "sparta express"
Please. 10% increase of gravity is nothing. I bet with a little training you could easily walk in that train during both phases. And even if you have to stay buckled down and can`t eat/drink (and I`m sure you can) - it`s only a hour. People who commute to work by car subject themselves to such horrors every day... Just think of the accelerations\braking when traffic lights change - it is worse than my vactrain.
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Old October 4th, 2010, 08:14 PM   #3469
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Hewu Railway opened for service on September 29

Hewu Railway (freight only)
- Route: Hesigewula Coal Mine – East Ujimqin Banner, Inner Mongolia
- Length: 313.3 km
- Investment: CN¥4.2 billion
- Capacity: 60 million ton per year
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Old October 4th, 2010, 08:43 PM   #3470
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Yichang-Wanzhou

Now that Shanghai-Hangzhou and Guangzhou-Shenzhen are both delayed, is Yichang-Wanzhou on schedule to open on 20th of November?
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Old October 4th, 2010, 09:23 PM   #3471
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Quote:
Originally Posted by Vanzetti View Post
Please. 10% increase of gravity is nothing. I bet with a little training you could easily walk in that train during both phases. And even if you have to stay buckled down and can`t eat/drink (and I`m sure you can) - it`s only a hour. People who commute to work by car subject themselves to such horrors every day... Just think of the accelerations\braking when traffic lights change - it is worse than my vactrain.
Typical trains today operate with a maximum acceleration of 0.5 m/s² .
0.75 m/s² is the value observed for most recent suburban trains, those
that must accelerate fast because they stop often. This is already enough
to cause problems to standing passengers, so I do not believe that 1m/s²
will ever be practical in day to day circumstances.

Last edited by MarcVD; October 4th, 2010 at 09:42 PM.
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Old October 4th, 2010, 10:00 PM   #3472
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Speed-time graph, Nanjing–Shanghai non-stop high-speed train
- Train: G7015 (CRH3-070C)
- Departure: Nanjing Station, 2010-09-05 12:59:42
- Arrival: Shanghai Station, 2010-09-05 14:18:47
- Total distance: 301 km
- Total time: 79 minutes (75 minutes on timetable)
- Maximum speed: 348 km/h

Nanjing–Shanghai HSR line uses old stations located in urban areas, so it had to slow down in cities. The train was 3 minutes late, it might be due to another train occupied its platform in Shanghai Station, this train had to wait until it is available. Trains for Shanghai Hongqiao Station should be unlikely affected by platform occupation since Hongqiao is high-speed train only.

The trip time will be cut to just below one hour when Beijing–Shanghai HSR is ready in 2011. The distance will be 285 km from Nanjing South to Shanghai Hongqiao on the future line.




Last edited by yaohua2000; October 4th, 2010 at 10:19 PM.
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Old October 5th, 2010, 01:35 AM   #3473
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Quote:
Originally Posted by Vanzetti View Post
Please. 10% increase of gravity is nothing. I bet with a little training you could easily walk in that train during both phases. And even if you have to stay buckled down and can`t eat/drink (and I`m sure you can) - it`s only a hour. People who commute to work by car subject themselves to such horrors every day... Just think of the accelerations\braking when traffic lights change - it is worse than my vactrain.
Wait, you mean you drive your car with over 1G ac/de-celaration??? I am not a good driver, but even I can't make it to 1G in bad traffic even if I tried... I must be doing something wrong or maybe my car is not good enough

Last edited by Ariel74; October 5th, 2010 at 01:43 AM.
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Old October 5th, 2010, 01:41 AM   #3474
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Quote:
Originally Posted by yaohua2000 View Post
...
Interesting data. Doesn't that show it's a mistake to have the route built to 350km/h standards? 250-300km/h would be more than enough.

When the Jinghu line opens, there will be an ultra-fast service between Nanjing and Shanghai anyhow, with top speed up to 380km/h. Wouldn't it be better to use the intercity line for medium-speed, high frequency, and all-stops services, instead?
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Old October 5th, 2010, 01:45 AM   #3475
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Quote:
Originally Posted by MarcVD View Post
Typical trains today operate with a maximum acceleration of 0.5 m/s² .
0.75 m/s² is the value observed for most recent suburban trains, those
that must accelerate fast because they stop often. This is already enough
to cause problems to standing passengers, so I do not believe that 1m/s²
will ever be practical in day to day circumstances.
You underestimate his ambitions. He's talking about acceleration above 1G, not the paltry 1m/s/s you are taking about
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Old October 5th, 2010, 02:16 AM   #3476
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Quote:
Originally Posted by Ariel74 View Post
Interesting data. Doesn't that show it's a mistake to have the route built to 350km/h standards? 250-300km/h would be more than enough.

When the Jinghu line opens, there will be an ultra-fast service between Nanjing and Shanghai anyhow, with top speed up to 380km/h. Wouldn't it be better to use the intercity line for medium-speed, high frequency, and all-stops services, instead?
Station sections can be developed in future as long as you have 7000m turn radius standard for your line. It can be seen as "future proof" solution.
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Old October 5th, 2010, 02:25 AM   #3477
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Quote:
Originally Posted by Ariel74 View Post
Interesting data. Doesn't that show it's a mistake to have the route built to 350km/h standards? 250-300km/h would be more than enough.

When the Jinghu line opens, there will be an ultra-fast service between Nanjing and Shanghai anyhow, with top speed up to 380km/h. Wouldn't it be better to use the intercity line for medium-speed, high frequency, and all-stops services, instead?
That was the original plan actually, the Shanghai-Nanjing intercity line opened with only 2 nonstop trains a day, which would be ok once the Jinghu line opened, but then people complained and now the SH-NJ line is serving all sorts of traffic now. Once the Jinghu line opens most of the nonstop service will switch to it and the intercity line will probably revert to the old schedule
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Old October 5th, 2010, 11:00 AM   #3478
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Quote:
Originally Posted by MarcVD View Post
Typical trains today operate with a maximum acceleration of 0.5 m/s² .
0.75 m/s² is the value observed for most recent suburban trains, those
that must accelerate fast because they stop often. This is already enough
to cause problems to standing passengers, so I do not believe that 1m/s²
will ever be practical in day to day circumstances.
You are not supposed to stand in a vactrain. Although, since vactrain acceleration\deceleration will be constant for most of the time, you could. You`ll just feel as if the floor is inclined forwards or backwards (depends on the phase of the journey). Nothing handrails won`t fix.
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Old October 5th, 2010, 11:02 AM   #3479
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Quote:
Originally Posted by Ariel74 View Post
You underestimate his ambitions. He's talking about acceleration above 1G, not the paltry 1m/s/s you are taking about
No, only the total "acceleration" (including Earth gravity) will be above 1G. The train itself accelerates at 5/m/s/s, or 0.5G.
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Old October 5th, 2010, 11:03 AM   #3480
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Quote:
Originally Posted by Ariel74 View Post
Wait, you mean you drive your car with over 1G ac/de-celaration??? I am not a good driver, but even I can't make it to 1G in bad traffic even if I tried... I must be doing something wrong or maybe my car is not good enough
No, it means you are a good driver. I tend to slam the brakes...
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