Question

The 60 kg block A and 20 kg block B are connected by a rope as shown in Figure 2 with the friction coefficients μs = 0.25 and μk = 0.20. 

  

1. Draw the free body diagram for each block.

b) If the weight of block B is unknown, determine the range of tension exerted on the rope to maintain the block from moving. 

c) If weight of block A is increased by 50%, determine whether the system is still in equilibrium. 

Answer 1

b) By Newton's second law:

$$-M_Bg+T=0,\\ T=M_Bg=20·9.8=196\text{ N}.$$

c) Find the frictional force for the increased weight:

$$f_s=\mu_s(1.5M_A)g=221\text{ N}.$$

The system will be in equilibrium.