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Homework Help: Newton's laws of motion -- Constaint motion

  1. Jun 28, 2017 #1
    1. The problem statement, all variables and given/known data
    In the following diagram a massless pulley is pulled by a constant force of magnitude P. There is no friction between the block and the floor. The acceleration produced in the block if mass m is? PIC ATTACHED

    2. Relevant equations
    Took a1/2=a2 where a1 is accn of block and a2 is accn of pulley since a3 that is accn of the string attached to wall is 0

    3. The attempt at a solution
    tried solving by taking acceleration but found that pulley is massless so I'm pretty confused atm and pls help me and clear my doubt

    Attached Files:

  2. jcsd
  3. Jun 28, 2017 #2
    Answer is P/2M but i end up getting P/M
  4. Jun 28, 2017 #3
    If P is the force pulling the pulley, what is the tension in the wire?
  5. Jun 28, 2017 #4
    That is not given sir...and P is the force pulling pulley
  6. Jun 28, 2017 #5
    Have you drawn a free body diagram of the pulley, or do you feel that you have advanced beyond the point where you need to use free body diagrams? From a free body diagram of the pulley, what are the three forces acting on the (massless) pulley?
  7. Jun 28, 2017 #6
    Yes sir P is the force on the pulley,
    Tension is not given..I calculated it as MG as There does not exist any other force that exists on M (surface is frictionless)
  8. Jun 28, 2017 #7
    I hv drawn it..just had the doubt that Is P=2T?
  9. Jun 28, 2017 #8
    Let's see your diagram.
  10. Jun 28, 2017 #9
    You don't think that the wire tension is acting on the mass?
  11. Jun 28, 2017 #10
    Of course sir

    Attached Files:

  12. Jun 28, 2017 #11
    Yes sir i just uploaded the fbd
  13. Jun 28, 2017 #12
    Is it correct...By doing this i get the answer
  14. Jun 28, 2017 #13
    So, as you have found from your fbd, P=2T. So, ma=T=P/2
  15. Jun 28, 2017 #14
    Wow!....I calculated it myself... Hats off to ur organization sir...Really obliged to get to know about ur organization ..Will surely recommend it to others
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