A system comprised blocks, a light frictionless pulley, and ...

[vinney12]

A system comprised blocks, a light frictionless pulley, and connecting ropes is shown in the figure. The 9.0-kg block is on a perfectly smooth horizontal table.
 
  The surfaces of the 12-kg block are rough, with between the block and the table. If the 5.0-kg block accelerates downward when it is released, find its acceleration.
 
  A) 1.0 m/s2
  B) 1.2 m/s2
  C) 1.4 m/s2
  D) 1.6 m/s2
  E) 1.8 m/s2

Question 2

Block A of mass 5.0 kg and block X are attached to a rope which passes over a pulley, as shown in the figure. An 80-N force P is applied horizontally to block A, keeping it in contact with a rough vertical face.
 
  The coefficients of static and kinetic friction between the wall and block A are s = 0.40 and k = 0.30. The pulley is light and frictionless. The mass of block X is adjusted until block A moves upward with an acceleration of 1.6 m/s2. What is the mass of block X?
 
  A) 9.9 kg
  B) 9.3 kg
  C) 8.7 kg
  D) 8.1 kg
  E) 7.5 kg

[mfedorka]

Answer to Question 1

Answer: A

Answer to Question 2

Answer: A

[vinney12]

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[mfedorka]

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