Posted by Nate on Sunday, May 27, 2012 at 6:50pm.
You push your couch a distance of 3.6 m across the living room floor with a horizontal force of 198.0 N. The force of friction is 151.0 N. What is the work done by you, by the friction force, by gravity, and by the net force?

Physics  bobpursley, Sunday, May 27, 2012 at 6:55pm
by you: 198*distance
by friction: 151*distance
by gravity: zilch
net force= force pushingfrictionforce 
Physics  Delbarre, Sunday, May 27, 2012 at 7:05pm
W=F.d , W= (198.0N)(3.6m)cos 0, W=712.8 N.m
this is your work.
W=(151.0N)(3.6)cos 180, W=(1)543,6N.m
this work is negative because the force of friccion is opposite a the direction of movement y therefore the angle is 180
for last the total work is the sum of the all work
PS: the work of gravity is perpendicular
a the movement therefore cos 90 = 0.
Work gravity is 0
enjoy your answer.