A 5.080 kg block of wood rests on a steel desk. The coefficient of static friction between the block and the desk is ?s = 0.505 and the coefficient of kinetic friction is ?k = 0.255. At time t = 0, a force F = 15.5 N is applied horizontally to the block. State the force of friction applied to the block by the table at the following times: t=0 and t>0