Consider a block of mass \(m\) hanging using a string and pulley arrangement, as shown in the figure. The weight \(mg\) and tension \(T\) are working on the block in such a way that the block is not moving and the string is parallel to the perfectly vertical wall. If the block is just in contact but not attached/fixed with the wall and the coefficient of static friction is \(\mu\), then the static frictional force acting on the block is
