Difficulty over a mechanism with friction

How can I solve this problem below. The mechanism shown is acted upon by the force P of magnitude P=20 lb. Knowing that teta=25 degree and that the coefficient of static friction between collar C and the horizontal rod is 0.30, determine the range of values of Q for which equilibrium is maintained. I included the mechanism drawing with this question. The answer of this problem for your verification is: 20.6 lb< Q <46.0 lb

PID= water controller

What i really want is to design a mathematical model to control the level of water in a water tank. And based on that the following two models. 1) Controlling the level of liquid in a water tank using mathematical model 2) PID controller for controlling the level of liquid in a water tank using the same mathematical model equations

Statics - Finding Force Exerted and Reaction

A small hoist is mounted on the back of a pickup truck and is used to lift a 12--kg crate.Determine (a) the force exerted on the hoist by the hydraulic cylinder BC, (b) the reaction at A. FOR DIAGRAM PLEASE SEE ATTACHED

Measuring Tension (Mechanical Eng.)

The 10-kg square plate shown is supported by three vertical wires. Determine the tension in each wire when a = 65mm. (FOR DIAGRAM PLEASE SEE ATTACHED)

constant torque

Attached you will find the problem that I have been working on and the work that I have compleated so far. I do not know how to do part 4 and also could you check over the work that i have compleated. thanks