A System of Blocks and a Frictionless Pulley Is Shown

Multiple Choice

A system of blocks and a frictionless pulley is shown in the figure. Block A has a mass of 2.0 kg and is on a rough horizontal surface for which μ_s = 0.40 between the surface and block A. The rope pulls horizontally on block A. Block C has a mass of 1.0 kg. An external force P = 23.0 N, applied vertically to block A, maintains the system at rest as shown in the figure. What is the friction force on block A?

A) 6.3 N
B) 6.9 N
C) 7.5 N
D) 5.7 N
E) 5.1 N