Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

bii17

  • 3 years ago

A weight is attached to one end of a 33 foot rope which passes over a pulley 18 feet above the ground. the other end is attached to a truck at a point 3 feet above the ground. if the truck moves away at a rate of 2 feet per second, how fast is the weight rising when the truck is 8 feet from the spot directly under the pulley?

  • This Question is Closed
  1. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1349004422200:dw|

  2. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1349004500723:dw|

  3. bii17
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I need a solution :)

  4. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    which direction is the trick moving, it is not clear

  5. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349004602933:dw|

  6. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1349004739213:dw|

  7. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349004667017:dw|

  8. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349004778629:dw|

  9. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    dx/dt =2 feet per second y is constant..... now, can u find dh/dt

  10. bii17
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    how?

  11. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349004927462:dw|

  12. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Since y is constant dy/dt=0 right?

  13. bii17
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes. then?

  14. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349005061647:dw|

  15. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Now, given x=8

  16. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    y=18-3=15

  17. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    So, |dw:1349005186713:dw|

  18. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    right?

  19. bii17
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @sauravshakya the answer is 16/ 17

  20. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Use of calculus is good

  21. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349005396208:dw|

  22. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Now we need to find dl/dt

  23. bii17
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    how to fnd it @sauravshakya

  24. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    you need a better diagram

  25. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    A weight is attached to one end of a 33 foot rope which passes over a pulley 18 feet above the ground. the other end is attached to a truck at a point 3 feet above the ground. if the truck moves away at a rate of 2 feet per second, how fast is the weight rising when the truck is 8 feet from the spot directly under the pulley?

  26. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349005616181:dw||dw:1349005671316:dw|

  27. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Did I did some algebra wrong or what???????

  28. bii17
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    hmm i dont know.. the answer should be 16/ 17

  29. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1349005592570:dw|

  30. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    x is the distance the weight has been raised, and y is the horizontal distance, where the rope is attached, to the vertical line passing through the pulley.

  31. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    its ok

  32. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    @bii17 u sure the answer is 16/17

  33. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    its correct

  34. bii17
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @sauravshakya yes im sure. that is the answer given in the book

  35. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    But I got 16/15 @goformit100

  36. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    i did the calculation @sauravshakya is correct now

  37. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    @ganeshie8 if u r free PLZ see this

  38. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @Callisto check it

  39. goformit100
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    plz

  40. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    @hartnn can U plz check it

  41. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh i will do it again

  42. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1349007585718:dw|

  43. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    15 ^2 + x^2 = (33- y)^2

  44. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    y is the height that the weight rises from the ground. , x is the distance the truck has moved to the left

  45. hartnn
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1349007886322:dw| @sauravshakya

  46. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    did you get 16/17?

  47. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Oh ya....... @hartnn

  48. hartnn
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    that still doesn't give answer.....

  49. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    Yep

  50. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    15 ^2 + x^2 = (33- y)^2 2x *dx/dt = 2 ( 33 - y) * (-dy/dt) x * dx/dt = (33-y) * (-dy/dt) x/ (33-y) * dx/dt = -dy/dt , this works

  51. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    8 / ( 33 - 16 ) * 2 = 16/17 , x = 8 , that is given, y = 16 by plugging in 15^2 + x^2 = (33-y)^2

  52. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    the only weird part is the negative sign

  53. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    @hartnn that gives the answer

  54. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh nevermind, it should be plus

  55. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    15^2 + x^2 = (33+y)^2

  56. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1349008213306:dw|

  57. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1349008265370:dw|

  58. sauravshakya
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 3

    So,|dw:1349008256578:dw|

  59. hartnn
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes it does, u did it @sauravshakya ! :)

  60. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes that is simpler. the trick is to see that y is constant

  61. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    |dw:1349008430327:dw|

  62. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    y = 15,

  63. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    wait, dh/dt is the rate at which the rope is being pulled

  64. perl
    • 3 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so dh/dt = the rate at which the weight is moving up ? interesting

  65. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy