Sol. When the pulleys are rotating in a clockwise direction, the belt is in contact with a larger part of each of the pulleys, since the lower part of the belt is pressed on to the pulleys as a result of being stretched, while the upper part of it bends under its own weight (fig.a). Therefore the force of friction will be greater and the belt will begin to slip on the pulleys only when a greater load is applied; therefore more power can be transmitted than when the pulleys are revolving in a counter-clockwise direction (fig.b).