........................z......
The general formula to calculate the work is:
where F is the force, d is the displacement of the couch, and 
is the angle between the direction of the force and the displacement. Let's apply this formula to the different parts of the problem.
(a) Work done by you: in this case, the force applied is parallel to the displacement of the couch, so 
and 
, therefore the work is just equal to the product between the horizontal force you apply to push the couch and the distance the couch has been moved:
(b) work done by the frictional force: the frictional force has opposite direction to the displacement, therefore 
and 
. Therefore, we must include a negative sign when we calculate the work done by the frictional force:
(c) The work done by gravity is zero. In fact, gravity (which points downwards) is perpendicular to the displacement of the couch (which is horizontal), therefore 
and 
: this means
.
(d) Work done by the net force:
The net force is the difference between the horizontal force applied by you and the frictional force:
And the net force is in the same direction of the displacement, so and and the work done is
Answer:
conservative
Explanation:
Nonconservative force is the force that depends on a path, however conservative does not depend on a path and it is not associated with the potential energy. When the work is done by an unconservative force, mechanical energy is added or removed. Friction is the best example for a non-conservative force. When these non-conservative forces are acting, the mechanical energy changes but these are not preserved.
hope this helped!
