Question

Blocks A, B and C are placed as shown in figure and connected by ropes of negligible mass. Both A and B weigh 25.0 N each, and the coefficient of kinetic friction between Block A and B and the surface is 0.35. Block C descends with constant velocity. Assume massless and frictionless pulleys.

a. Draw the free-body diagrams of each of the objects.

b. Find the tension in the rope connecting blocks A and B.

c. What is the weight of block C?

d. If the rope connecting A and B were cut, what would be the acceleration of C?

Answer 1

a)

b)

$$T_1=\mu N_A=(0.35)(25)=8.75\ N$$

c)  The weight of blockC will be the tension in the rope connecting B and C

$$w_c=T_2=9+w_B(\sin{37}+0.35\cos{37})=31\ N\\$$

d) Appling Newton's second law to the remaining massese (B and C) gives

$$a_c=g\frac{w_c-\mu w_b\cos{37}-w_b\sin{37}}{w_b+w_c}=1.6\frac{m}{s^2}$$