Attn Smarty-Pants Mags

[pepperdawg]

At 4pm a train leaves Kansas City heading west at 55 MPH. At 4:45 on the same track time a train leaves Denver heading east at 35 MPH….What time will they collide?


Need answer for 10AM Eastern today. Show work for extra credit

[JimmyCarter]

Is the treadmill moving east to west or west to east?

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[Timberridge]

If it's Amtrak one will derail on a curve first.

[smartyiak]

This thread about me?

Just checking in.

Oh: they won't collide b/c the plane will take off.

[Sirshredalot]

Is the treadmill moving east to west or west to east?

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Yes.

[Timberridge]

It's 10 AM

[bw_wp_hedonism]

Were they supposed to collide at 10am, or was an answer to be given by 10am?

[Supermoon]

At 4pm a train leaves Kansas City heading west at 55 MPH. At 4:45 on the same track time a train leaves Denver heading east at 35 MPH….What time will they collide?


Need answer for 10AM Eastern today. Show work for extra credit

They are covering 90 miles of track per hour, so take the distance, divide by 90 and you have your travel time. Add that to 4:45 and there you go.

[Timberridge]

They are covering 90 miles of track per hour, so take the distance, divide by 90 and you have your travel time. Add that to 4:45 and there you go.

Denver is MDT, and KC is CDT

Were they supposed to collide at 10am, or was an answer to be given by 10am?

If the former, may god rest their souls.

[shafty85]

They are covering 90 miles of track per hour, so take the distance, divide by 90 and you have your travel time. Add that to 4:45 and there you go.

You also need account for the 45min of travel at 55mph prior to the second train leaving. So, what ^^^ said, but the distance to divide by 90 is original distance - 41.25 miles.

[Supermoon]

You also need account for the 45min of travel at 55mph prior to the second train leaving. So, what ^^^ said, but the distance to divide by 90 is original distance - 41.25 miles.

Oh right. Reading comprehension fail.

[pepperdawg]

Smarty Pants Dentists - Thx

[SumJongGuy]

Still the question of will they be in Mountain Time or Central time? It was 4 PM Central when KC train left., It was 4:45 Mountain when Denver train left.. so Denver train actually left an hour and 45 minutes before the KC train left right?? It was only 3PM in Denver when the KC train left right? And, what time zone will they be in when they collide?

[hutash]

First off, there is an assumption they are on the same track, but that is not stated in the problem, so they will most likely never run I to each other. We also need to know which railroad is the running the trains and there on time records. Amtrak will be late, as always.

[GeezerSteve]

It's a trick question. The trains will not collide. One of the trains will slip into a siding track, allowing the other train to safely pass on the main line. It happens hundreds of times each day in America.

[Timberridge]

First off, there is an assumption they are on the same track, but that is not stated in the problem

Ahem...

At 4:45 on the same track time a train leaves Denver

There is an assumption that the track exists in a straight line between KC and Denver. Any deviation could screw up the distance calculation. This problem is very hard to solve without access to detailed track layouts between the two cities.

[Supermoon]

There is an assumption that the track exists in a straight line between KC and Denver. Any deviation could screw up the distance calculation. This problem is very hard to solve without access to detailed track layouts between the two cities.

I don't think that's necessarily true as long as you create a confidence interval.

So if we declare our assumptions:
1) The trains WILL collide. It's stipulated in the problem, but there seems to be some confusion here.
2) The distance between the two cities by train closely resembles the driving distance. My assumption here is that major freeways will follow nearly the same route as major freight corridors.
3) If we are dealing with American train systems, it's only fair to give a +/- of 5 minutes to the times. That gives us 11 minutes (and 16.5 miles) of leeway, which more than covers any distance discrepancy. As you can see from Google maps, even taking I-80 to get between the two cities instead of I-70 only adds about 25 miles.

4) We have to assume acceleration is either instantaneous, or close enough to instantaneous to not matter in the formula.
5) When the problem says 4:45, they actually mean 4:45 pm Mountain Time - we can know this because of assumption #1.

Our variables:
x = time traveled by the Westbound train
d = total distance traveled of 651 miles per Google
a = speed of EB train leaving at 3:45 pm Central at 35 mph
b = speed of WB train leaving at 4 pm Central at 55 mph

It's an average speed problem, so generally it will that the form of distance over time: d/t, but has to take into account the extra 15 minutes of travel by the EB train.

f(x) = [651 - (35/4)]/[35x+55x}

f(x) = 642.25/90x

x= 7.136 hours or approximately 7 hours and 8 minutes and 10 seconds, which would make it 11:08:10 pm Central, +/- 10 minutes.

I clearly have too much time on my hands this morning.

[pepperdawg]

Forgot to add - trains are running on Metric time. my bad.

[Supermoon]

Forgot to add - trains are running on Metric time. my bad.

Then the answer is 0.02568960072 megaseconds.

[booner]

October

[k2skier112]

12:12

[billyk]

Where do they bury the survivors?

[SumJongGuy]

42

[Bunion 2020]

African Swallow or European Swallow?

[JimmyCarter]

Forgot to add - trains are running on Metric time. my bad.

Not in my America goddamit.