Question

A bar of mass m is pulled by means of a thread up an inclined plane forming an angle α with the horizontal (Fig. 1.13). The coefficient of friction is equal to k. Find the angle β which the thread must form with the inclined plane for the tension of the thread to be minimum. What is it equal to?

Answer 1

Let us fix the x-y coordinate system to the wedge, taking the x-axis up, along with incline and the y-axis perpendicular to it (Fig.).