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Homework Help: Mechanical advantage, acceleration, work, power

  1. Dec 10, 2009 #1
    Basically i have no clue how to do this so I was hoping someone could help me on the formulas with some and explain/show how to set it up. Thanks :)

    1. a block and tackle (a system of pulleys) with a mechanical advantage of 48 is used to life a piano 11 m to the third floor of a building. Although the pullets in the block and tackle make it easy to lift it still takes a long time because of the length of the rope. What is the length? (hint: its the input distance)

    2. the whale shark is the largest of all fish and can have the pass (I believe she meant mass) of three adult elephants. Suppose that a crane is lifting a whale shark for delivery to an aquarium. The crane exerts a force of 2.5*104N to lift the shark from rest. If the shark's acceleration equals 1.25 m/s2, what is the sharks mass?

    3. Suppose a meteorite collides with Earth with a force of 6.41*1012N.

    A. What is the mass of the meteorite if it's impact speed is 10 km/s so that it has an acceleration of approximatley -1.00*108 m/s2

    P.S. I'm not trying to take the easy way out and cheat the thing has about 50 problems so I'm just trying to get some examples because I don't understand this section of my review and I don't want to do bad on the final.
     
    Last edited: Dec 10, 2009
  2. jcsd
  3. Dec 10, 2009 #2
    Use F=ma!
     
  4. Dec 10, 2009 #3
    I'm going to be honest idk what that is. I'm guessing Force=Mass*Acceleration?
     
  5. Dec 10, 2009 #4
    3- u may use simply the newton'ssecond law..velocity has nothing to do with the force since acceleration is given just divide force by accelaration to get the mass
     
  6. Dec 10, 2009 #5
    1- MA=(effort distance/load distance) just use the formula to claculate here load distance is 11m and MA is 48 so effort distance or length of rope is 48*11
     
  7. Dec 10, 2009 #6
    Yup!
     
  8. Dec 10, 2009 #7
    So since I want mass it would be mass=force/acceleration?
     
  9. Dec 10, 2009 #8
    Yes.
     
  10. Dec 10, 2009 #9
    ah thank you everyone
     
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