A Box Is in Contact with a Surface That Makes

Multiple Choice

A box is in contact with a surface that makes an angle of 30^o with the horizontal. An applied horizontal force of 10.0 N allows the box to slide along the surface at a constant speed. When the box has moved 2.0 m along the surface, the work done on it by the normal force is

A) 0 J.
B) 10.0 J.
C) 20.0 J.
D) 40.0 J.
E) 60.0 J.