Chapter 12, Problem 7Q

In Fig. 12-20, a stationary 5 kg rod AC is held against a wall by a rope and friction between rod and wall. The uniform rod is 1 m long, and angle θ = 30°. (a) If you are to find the magnitude of the force $\stackrel{\to }{T}$ on the rod from the rope with a single equation, at what labeled point should a rotation axis be placed? With that choice of axis and counterclockwise torques positive, what is the sign of (b) the torque τ_w due to the rod’s weight and (c) the torqueτ_r due to the pull on the rod by the rope? (d) Is the magnitude of τ_r greater thankless than, or equal to the magnitude of τ_w?

Figure 12-20 Question 7.