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Calculating the speed of a crane (using pythagoras) with different x & y speeds

  1. Dec 28, 2010 #1

    1. The problem statement, all variables and given/known data

    I'm designing a C++ program to simulate the operation of a steel processing warehouse. Part of my code requires me to calculate the time it takes for a crane to move certain distances (mainly diagonal ones) across a large shelving rack.

    2. Relevant equations
    The crane moves at different speeds in different directions.
    Maximum x speed = 40m/min
    Maximum y speed = 12.5m/min

    I was thinking of using pythagoras theorem somehow to solves this (although its not required to be done this way) so:
    c2 = a2 +b2

    3. The attempt at a solution
    I was thinking of using:

    time = distance/speed

    to calculate the time for each movement in x direction and y direction. Then using pythagoras theorem on the times to get the diagonal movement time. So an example would be:


    X-Time = 6/40 = 0.15min
    Y-Time = 4/12.5 = 0.32min

    Z-Time = SQRT(0.152+0.322) = 0.353min

    Would that be correct? Im not sure if i can apply pythagoras theorem to time like that. Any Help is appreciated

  2. jcsd
  3. Dec 28, 2010 #2

    I would use Pythagorean theorem on the velocity and distance. Then use t = d/v. You would find how far the crane moves along the diagonal, and if the x-y speeds are constant, how fast it is moving along the diagonal so you could calculate the time.
  4. Dec 28, 2010 #3
    Thank you for the reply Apphysicist :)

    Ahh right, i see. Tried out your method and got the following:

    ZDistance = SQRT(42 + 62) = 7.211
    ZSpeed = SQRT(402 + 12.52) = 41.907

    t=d/v = 7.211/41.907 = 0.17min

    That seems a bit quick doesnt it? given that the previous results were:
    X-Time = 0.15min
    Y-Time = 0.32min

    i would have thought the pythagoras time would be closer to the slowest time. No?
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