The machine as shown has 2 rods of length 1   m connected by a pivot at the top. The end of one rod is…

The machine as shown has 2 rods of length 1 m connected by a pivot at the top. The end of one rod is connected to the floor by a stationary pivot and the end of the other rod has roller that rolls along the floor in a slot. As the roller goes back and forth, a 2 kg weight moves up and down. If the roller is moving towards right at a constant speed, the weight moves up with a :

  1. Speed which is 34th of that of the roller when the weight is 0.4 m above the ground
  2. Constant speed
  3. Decreasing speed
  4. Increasing speed

Solution



vA=dxdt=d2lcosθdt=-2lsinθdθdt and 

Vertical velocity of B, vB=dydt=dlsinθdt=lcosθdθdt

vAvB=-2tanθ⇒vB=-vAcotθ2 
 
θ→increase

cotθ→decrease

Hence, vB→decrease.

Asked in: JEE Main 2017 (09 Apr Online)

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