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What is the mass of block on the left?

  1. Sep 29, 2007 #1
    1. The problem statement, all variables and given/known data

    The 100kg block in the figure below takes 6.6s to reach the floor after being released from rest. What is the mass of block on the left?

    http://i241.photobucket.com/albums/ff4/alg5045/p8-33.gif

    2. Relevant equations

    F=ma
    kinematic equation

    3. The attempt at a solution

    I tried using accleeration = velocity/time, and I got .023 m/s^2. Then I used velocity = displacement/time, and I got .152 m/s. And then I got completely lost.
     
  2. jcsd
  3. Sep 29, 2007 #2
    You should be using
    d = 0.5at^2 (assuming that initial v is 0)

    so get a, and then
    you know the system is moving with a

    therefore weight of larger mass - wieght of smaller mass = (total mass)*a
     
  4. Sep 29, 2007 #3
    Ok, for the acceleration I got .046m/s^2. How do I figure out what the total mass is since I don't know the smaller mass?
     
  5. Sep 29, 2007 #4

    learningphysics

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    Homework Helper

    you want to solve for the smaller mass... write the total mass in terms of the smaller mass...
     
  6. Sep 29, 2007 #5
    So larger mass-smaller mass = (larger mass + smaller mass)a
     
  7. Sep 29, 2007 #6

    learningphysics

    User Avatar
    Homework Helper

    (larger mass)*g - (smaller mass)*g = (larger mass + smaller mass)a
     
  8. Sep 29, 2007 #7
    Got it after three tries at manipulating the equation. 99.067kg.
     
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