posted by josh on .
find the frictional force exerted on a 20kg block pulled slowly over a horizontal floor using a rope which makes a 30 degree angle over the horizontal. the pulling force is 100N???
i found the Fn to be 146 N what do i do from there?
You want the frictional force, not the normal force.
100* cos 30 = 86.6 N
is the frictional force, since it is being pulled slowly and presumably not acclerating. You don't need to use the mass information to get that.
The normal force is
M g - 100N sin 30 = 146 N; you were right about that.
The coefficient of sliding friction is 86.6/146 = 0.59