I got 89%, but I'm not buying this BS:
<< 6. To keep a heavy box sliding across a carpeted floor at constant speed, a person must continually exert a force on the box. This force is used primarily to overcome which of the following forces?
d. The gravitational force exerted by the Earth on the box. is not correct. The correct answer is:
c. The frictional force exerted by the floor of the box.
52 percent of students answered correctly >>
Where the hell do they think the "friction" comes from? If there were no gravity, there would be no friction.
Russ, NCNE