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anonymous

  • one year ago

sand is poured on a conical pile at a rate of 20 m^3/min. The height of the pile is always equal to the radius of the base of the pile. When the pile is 3m high, how fast is the height of the pile increasing?

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  1. imqwerty
    • one year ago
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    dv/dt=20 m^3/minute we r given that radius=height, so radius=3=heoght :) Volume of cone=1/3(πr^2h) now Volume=1/3π9h dv/dt=1/3(9)dh/dt dv/dt=3dh/dt dv/dt=3dh/dt we know that dv/dt=20 so 20=3dh/dt dh/dt=20/3

  2. anonymous
    • one year ago
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    how did you get the now volume?

  3. anonymous
    • one year ago
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    oh it's radius sorry :))

  4. anonymous
    • one year ago
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    *the

  5. imqwerty
    • one year ago
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    it is given in the question that height of pike is ALWAYS equal to radius of pile :)

  6. imqwerty
    • one year ago
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    *pile

  7. anonymous
    • one year ago
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    why was the π gone in dv/dt=1/3(9)dh/dt? :)

  8. anonymous
    • one year ago
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    @imqwerty

  9. imqwerty
    • one year ago
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    yea pi shuld also come sry

  10. anonymous
    • one year ago
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    the answer should be 20/3π? :)

  11. imqwerty
    • one year ago
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    yea

  12. anonymous
    • one year ago
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    oh it's not in the choices :(

  13. imqwerty
    • one year ago
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    what r the choices?

  14. anonymous
    • one year ago
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    the choices are : 1.42, 0.71, 0.66 and 1.32

  15. imqwerty
    • one year ago
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    something went wrng jst a min

  16. anonymous
    • one year ago
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    oh it's supposed to be 20/9π :)

  17. anonymous
    • one year ago
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    dv/dt = 1/3πr^(3)

  18. imqwerty
    • one year ago
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    how?

  19. anonymous
    • one year ago
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    |dw:1441469657321:dw|

  20. anonymous
    • one year ago
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    dv/dt = πr^(2)dh/dt

  21. imqwerty
    • one year ago
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    :O okay :)

  22. anonymous
    • one year ago
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    dv/dt = π(9) dh/dt then plug in 20 for dv/dt

  23. anonymous
    • one year ago
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    thank you guys for helping me :)

  24. imqwerty
    • one year ago
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    no prblm :D

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