text: # Mechanics help !
  
  1. Nov 24, 2011
  
  ### awesome4444
  
  Mechanics help :(!
  
  I REALLY NEED HELP :(
  Two blocks are connected by a cord which passes over a frictionless pulley at D.
  Block A has a mass of 40 kg and block B a
  mass of 120 kg. A rests on a horizontal
  surface, while B rests on a ramp with the slope
  shown. B is initially in a position 3 m from the
  stop C as shown. The coefficient of kinetic
  friction between the blocks and the surface
  beneath is μK = 0.20 for both A and B.
  
  (a) Find the acceleration of the two blocks and
  the tension T in the cord, assuming that the
  blocks just begin to move at time t = 0.
  
  2. Nov 24, 2011
  
  ### grzz
  
  Re: Mechanics help :(!
  
  Diagram?
  
  3. Nov 24, 2011
  
  ### awesome4444
  
  4. Nov 24, 2011
  
  ### grzz
  
  Re: Mechanics help :(!
  
  First we draw the FBD for mass A and for mass B.
  
  How many forces act on each?
  
  5. Nov 24, 2011
  
  ### awesome4444
  
  Re: Mechanics help :(!
  
  on mass 1 we have forcetension - forcefriction + m*g = ma
  mass2 -frocetension-Forcefriction2+(m*g)sin theta= m2a
  
  the thing thats confusing me is if we could have assumed that the aceleration of B is same as acceleration of a before it hits the barrier in the diagram
  
  6. Nov 25, 2011
  
  ### grzz
  
  Re: Mechanics help :(!
  
  To avoid confusion, instead of mass 1 let us call it mass A as in diagram.
  
  Re 1st equation: I do not know why you have m*g.
  
  Until mass B hits the barrier at C we HAVE TO assume that the acceleration of B is the same (in magnitude) as that of A because otherwise the string either snaps or becomes slack and so there would not be any tension at all!
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