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Thread: Problem on Mathematics - continued

  1. #1

    Default Problem on Mathematics - continued

    After seeing an old thread about mathematics, I would like to post one too...

    There are 2 cars, 1km apart travelling towards each other with speed 10km/h until they crash head on. There's a bee that will travel in between the cars at the speed of 20km/h.

    How many times can the bee move back and forth between the cars before it got crushed in between?

    Assumptions
    - The bee can change direction with no time lack and acceleration is neligible.
    - The bee's starting point is with one of the cars.

    [Car A][Bee].................................................. ......................[Car B]
    ..........<---------------------- 1km --------------------------->

  2. #2
    vince123123
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    Default Re: Problem on Mathematics - continued

    Lol, everyone starting to post their homework questions here? :P HEHE

    Quote Originally Posted by Jenova View Post
    After seeing an old thread about mathematics, I would like to post one too...

    There are 2 cars, 1km apart travelling towards each other with speed 10km/h until they crash head on. There's a bee that will travel in between the cars at the speed of 20km/h.

    How many times can the bee move back and forth between the cars before it got crushed in between?

    Assumptions
    - The bee can change direction with no time lack and acceleration is neligible.
    - The bee's starting point is with one of the cars.

    [Car A][Bee].................................................. ......................[Car B]
    ..........<---------------------- 1km --------------------------->

  3. #3
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    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by vince123123 View Post
    Lol, everyone starting to post their homework questions here? :P HEHE
    School holiday again?

  4. #4

    Default Re: Problem on Mathematics - continued

    Couldn't help but try solving it...

    I think it's 0.05 hour (180 sec). Pls correct me if I'm wrong...
    Jia Wang... "A photo is only as beautiful as the photographer's eyes can see."
    My Eyes ;)

  5. #5
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    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by Jia Wang View Post
    Couldn't help but try solving it...

    I think it's 0.05 hour (180 sec). Pls correct me if I'm wrong...
    Wrong la, the question is how many times...

  6. #6

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by Astin View Post
    Wrong la, the question is how many times...
    Oops... haha sorry... too excited with the time taken... theoretically this value of 180s is based on an infinite geometric series... but in actual crash, the bee very likely won't survive more than 10 times
    Jia Wang... "A photo is only as beautiful as the photographer's eyes can see."
    My Eyes ;)

  7. #7
    Senior Member phoakm's Avatar
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    Default Re: Problem on Mathematics - continued

    50 times?
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  8. #8

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by phoakm View Post
    50 times?
    Depends on how fat our bee is
    Jia Wang... "A photo is only as beautiful as the photographer's eyes can see."
    My Eyes ;)

  9. #9
    Senior Member phoakm's Avatar
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    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by Jia Wang View Post
    Depends on how fat our bee is
    That bee must be full of honey!
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  10. #10
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    Default Re: Problem on Mathematics - continued

    LOL...ya it depends on how fat the bee is .... if not quite hard to do and make assumptions to solve.

    Anyway, if I'm not wrong, the distance between both cars will be 1/3 of the previous distance in between the time the bee reaches one car to another.
    Dun blame the camera...blame the one behind the viewfinder :bsmilie:
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  11. #11

    Default Re: Problem on Mathematics - continued

    Conditions of the problem cannot be met.

    Answer does not exist.

    ......... plus a few smilies to retain the light-hearted humour of this thread.

  12. #12

    Default Re: Problem on Mathematics - continued

    $50 for an answer. With graphics explaination included. U want?

  13. #13

    Default Re: Problem on Mathematics - continued

    the way to do this is to use relative velocity

    let's say the bee is on the left car

    imagine that car two is stationary, the bee will then be moving towards car two at a rate of 30 km/h (20+10)
    while car one is moving towards car two at a rate of 10+10 km/h, or rather 20km/h

    so what was mentioned earlier is right, everytime the bee reaches another car, the distance remaining is 1/3 of the original before they started moving
    this is because everytime it starts from one side, the bee takes 2/3 of the time the two cars need to cover to reach each other to reach the other car due to faster speed

    by gp,
    first time - 1/3 km distance left
    second time - 1/9 km distance left
    third time - 1/27 km distance left
    fourth time - 1/81 distance left

    and so and so forth

    so this is a stupid question, since even when distance between the two are minutely small, the bee is flying faster than the two cars' relative motion to each other.
    even if distance left is 0.01cm between the two when the bee has reached one of the two cars, the bee is just buzzing very fast in between the two

    answer is simply related to the amount of time taken for the two cars to meet, i.e. 1/20 hour or 3 minutes. because once they meet, confirm the bee gone case.
    in this three minutes, the bee can only fly 20/20 km = 1 km. because it is travelling at constant speed.

    but if you want the number of times the bee is going to be able to move back and forth in between, amazingly, it seems like the answer is infinite.
    Last edited by night86mare; 13th May 2008 at 07:52 PM.

  14. #14

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by Jenova View Post
    After seeing an old thread about mathematics, I would like to post one too...

    There are 2 cars, 1km apart travelling towards each other with speed 10km/h until they crash head on. There's a bee that will travel in between the cars at the speed of 20km/h.

    How many times can the bee move back and forth between the cars before it got crushed in between?

    Assumptions
    - The bee can change direction with no time lack and acceleration is neligible.
    - The bee's starting point is with one of the cars.

    [Car A][Bee].................................................. ......................[Car B]
    ..........<---------------------- 1km --------------------------->
    guess infinite?

  15. #15

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by richardg View Post
    guess infinite?
    you is copy my answer !




  16. #16

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by night86mare View Post
    you is copy my answer !



    aiyoh sollie forgot to check first..

    haha its one of those each time the distance is halved puzzle
    when will the twain meet?
    Last edited by richardg; 13th May 2008 at 09:45 PM.

  17. #17

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by richardg View Post
    haha its one of those each time the distance is halved puzzle
    when will the twain meet?
    ask them:




  18. #18
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    Default Re: Problem on Mathematics - continued

    Can be infinite only if the bee size is 0, so infinite is not the answer. The answer can only be known if the size of bee is known, just as the others already mentioned.
    D300 & P5100 :bsmilie:

  19. #19

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by rvxing View Post
    Can be infinite only if the bee size is 0, so infinite is not the answer. The answer can only be known if the size of bee is known, just as the others already mentioned.
    still infinite
    provided size of bee < 1km...

    a bit like fractals in reverse..
    universe can be as big and as small
    Last edited by richardg; 13th May 2008 at 10:07 PM.

  20. #20

    Default Re: Problem on Mathematics - continued

    Quote Originally Posted by richardg View Post
    still infinite
    provided size of bee < 1km...

    a bit like fractals in reverse..
    universe can be as big and as small
    yes

    the fact is relative velocity of bee to two cars is still faster.

    just when it's going to get squished, that's it's moment of glory, it will bounce between the two like a bat out of hell

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