Queue Problem

[crook]

This maybe a misfit here ! Biggie dare you touch this thread

Here is the problem: We have a 10 meter long queue of soldiers. The queue walked exactly 10 meters (that means the first person walked 10 meters ahead in a straight line and others followed). As soon as the queue had started moving, the last soldier ran up to the first soldier, passed on a message to him and ran back to his position (while the queue still moving ahead). He reached his position (last in the queue) exactly at the moment the queue had traveled 10 meters.

Question: What is the distance traveled by last soldier ?

[aashima]

Well the last soldier travelled 20 metres. Thats because the queue is 10 metres long. Being the last one, he would have to travel 10 metres to contact the first person and then again 10 metres back to his position. It should make any difference whether the queue is moving or still. All he needs to do is approach the first person and return back. Am I justified?

[The_Big_K]

Originally Posted by aashima

Well the last soldier travelled 20 metres. Thats because the queue is 10 metres long. Being the last one, he would have to travel 10 metres to contact the first person and then again 10 metres back to his position. It should make any difference whether the queue is moving or still. All he needs to do is approach the first person and return back. Am I justified?

Nope.

Read this -

..and ran back to his position (while the queue still moving ahead).

I guess the answer has to be less than 20 meters!

-The Big K-

[reachrkata]

I think the answer is 18 meters.

Am I right ???

[Jerry]

Originally Posted by reachrkata

I think the answer is 18 meters.

Am I right ???

I know the answer but do not want to spoil the fun. 18 meters is not the correct answer.

Jerry

[xheavenlyx]

NOTE: Highlight for the answer. But try solving first!

I think the answer is 30 meters!

the last guy walks the whole line and comes back too. thus w.r.t the line he has traveled 10(ffw)+10(bckward) meters andddd the total distance of the whole line had moved by 10 meters, so 10+10+10=30 meters.


This can also be justified by saying that since his speed was 2x or more then others while traveling back and forth keeping in mind he took the same time to rech the end of the que. Hence the distance will be somewhat more than others within the que. HOWEVER, his displacememnt will be the same! (10m)

[The_Big_K]

xHx - you sure that's the right answer? The last person took his position as soon as the queue had travelled 10 meters. That means, to reach the first person in the queue, he must have travelled 10+x (where x<10 ) meters.

I believe the answer is close to 20 meters. I'll try to patch in the complete answer later

Moreover, I guess the problem can be stated in a different way to remove the confusion. We'll have to ignore the path taken by the last person and assume that he travelled in straight line all the time.

Any thoughts?

-The Big K-

[xheavenlyx]

well you are right about the 10+x part, but rememeber he even had to return! and since the whole line is 10 meters itself, he HAD to cross that much distence no matter if they were stationary or running like asses. Going and comming is 10+10.

But i maybe wrong too, really difficult imagining. Had to draw ten step images

You might be confusing urself with displacement and distance maybe or mixing them up.

[crook]

Of course the final answer has to be 10+2x ; 'x' being the distance first person in the queue had travelled when the last person met him. I request everyone to put a detailed explanation along with your answer so that your post makes sense . No one posted the right answer so far.

Too tough for crazy engineers ?

[xheavenlyx]

Oh my last post must have been confusing, the answer i posted was 30m not 10+10. I used that post just to explain something. Acual one is in the top. (Queue Problem)

Anyway, you can post the anwer Getting impatient! But for now just the answer, dont explain yet.

( If we think in a simple way the distance by the first person is 5m when the messenger meets him. That gives the answer to be 10+2(5) = 20!! But I dont think thats the right answer. Aashima had given that... )