13). A block of mass Mis sliding with a constant velocity down a rough inclined surface which makes an angle - with the horizontal as shown in the figure at right. The coefficient of kinetic friction at the interface is &. Which M of the following statements about this situation are necessarily correct ? p). The magnitude of the force of friction acting on the block is * Mg cose. q). The magnitude of the force of friction acting on the block is Mg sine. "). Me - Tane. s). The net force acting on the block is zero. A). All of the above B). q, r, & s only ().p & r only Dj. p, r, & s only