a couple is on a bike tour along a railroad track. he has a problem with his bike, so he tells her "keep driving, ill catch up soon". when he fixed his bike he starts driving again. after a short time there comes a train, that needs 36 seconds to pass him completely. after another 18 seconds he can see how the beginning of the train reaches his wife, then there's a turn so she gets out of his sight.
when he reaches his wife, she tells him "i checked the time: from the moment the end of the train reached me, it took your 4 minutes to catch up with me."
now he wants to know, how much time the train needed to pass his wife? (they all had constant speed)
Originally posted by crazyblue a couple is on a bike tour along a railroad track. he has a problem with his bike, so he tells her "keep driving, ill catch up soon". when he fixed his bike he starts driving again. after a short time there comes a train, that needs 36 seconds to pass him completely. after another 18 seconds he can see how the beginning of the train reaches his wife, then ...[text shortened]... nts to know, how much time the train needed to pass his wife? (they all had constant speed)
I dont see how you can tell. The train or person could have changed speeds. You need to say the distances i think 😕
Originally posted by crazyblue a couple is on a bike tour along a railroad track. he has a problem with his bike, so he tells her "keep driving, ill catch up soon". when he fixed his bike he starts driving again. after a short time there comes a train, that needs 36 seconds to pass him completely. after another 18 seconds he can see how the beginning of the train reaches his wife, then ...[text shortened]... nts to know, how much time the train needed to pass his wife? (they all had constant speed)
Originally posted by crazyblue a couple is on a bike tour along a railroad track. he has a problem with his bike, so he tells her "keep driving, ill catch up soon". when he fixed his bike he starts driving again. after a short time there comes a train, that needs 36 seconds to pass him completely. after another 18 seconds he can see how the beginning of the train reaches his wife, then ...[text shortened]... nts to know, how much time the train needed to pass his wife? (they all had constant speed)
36s
I know it says the speed is constant but is the velocity? As I am assuming it is otherwise I couldn't tell.
Speed is a scalar value. It doesn't have a direction component. Velocity is a vector value, it contains both a direction component and a magnitude component. In this case you can assume that speed is constant (velocity isn't as there is a bend mentioned).
After working on this for a while I can't see how it can be solved. I've got equations for the solution but they contain both 'distance between the riders at the point where the end of the train reaches the man' and 'the length of the train'. Anything I try gives negative answers which can't be right.
Originally posted by TheMaster37 I need one more number.
Either the length of the train, the time the man needed for his fix or the distance between man and wife on the moment the train reached the man.
Was it a 2-8-8-0 steam loco? Was it an Amtrak Genisis 11 diesel? Was it an SNCF British class 91 electric or an LNWR "G" CLASS 0-8-0? That would help for the answer.
I got 30s using the solver function on MS Excel, but only after massaging the starting guesses to avoid negative solutions. I used 5 constants: v(man), v(woman), v(train), L(train), and dist0(woman-man) - I assumed the "short time" between the man starting up and the train arriving was 0. But regardless, there are more unknowns in this problem than pieces of information given (only 4). Therefore, as has already been stated in this thread, the problem is unsolvable.
how much time did the train need?
08 Jan '06 17:40
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