A 19.1 kg block is dragged over a rough, hor- izontal surface by a constant force of 195 N acting at an angle of angle 29.1 degrees above the horizontal. The block is displaced 30.3 m, and the coeficient of kinetic friction is 0.116. The acceleration of gravity is 9.8 m/s^2 . the question ask for he magnitude of work done by the force of friction. I found the force of friction to be 21.71 N and but the answer i'm getting for Work of frictional force is wrong. i dont know whats the matter, am i reading the problem wrong or sumtin? Work of Frictional force = Ffr(x)(cos180) i used 30.3 for x like the problem gave.