4. A block of mass m sliding down an incline at constant speed is initially at a height h above the ground, as shown in the figure. Thecoefficient of kinetic friction between the mass and the incline is μ.If the mass continues to slide down the incline at a constantspeed, how much energy is dissipated by friction by the time the mass reaches the bottom of the incline?
(A) mgh/µ
(B) mgh
(C) µmgh/ sin θ
(D) mgh sin θ
(E) 0