When two objects are in contact with no relative motion, which of the following statements about the frictional force between them is true? a. The frictional force is always equal to µsn. b. The frictional force is always less than µsn. c. The frictional force is equal to µkn. d. The frictional force is either equal to or less µsn.

1. Steve pushes a box across a level floor with a constant horizontal force. This causes the box to move at a constant speed, v. The force from Steve: a. has the same magnitude as the weight of the box. b. equals the sum of the box's weight and the total frictional forces opposing the box's motion. c. has the same magnitude as the frictional forces opposing the box's motion. d. has greater magnitude than the frictional forces opposing the box's motion. e. has greater magnitude than the weight of the box. 2. Steve now doubles the force he applies to th box from the previous problem. Which of the following is true? a. The box will move at double the previous speed. b. The box will move with a continuously increasing speed. c. The box will increase speed for a while, then move at a constant speed. d. The box will continue to move at the same speed for a while, then continually increase speed. e. The box will move at a greater constant speed, but not necessarily double the speed.

A person exerts a force of 120 NN on a rope that pulls a sled across a very smooth horizontal surface. The rope is oriented 37⁰0 above the horizontal. The sled has a total mass of 50 kgkg. The sled starts at rest and moves for 10 mm. Select all the quantities that can be determined using the given information. A. Determine the acceleration of the sled. B. Determine the normal force exerted by the surface on the sled. C. Determine the time taken for the sled to move 10 m. D. Determine the speed of the sled after moving for 10 m. F. Check all that apply. acceleration of the sled normal force exerted by the surface on the sled mass of the person time taken for the sled to move 10 mm speed of the sled after moving 10 mm

A restaurant manager pushes a box of melons horizontally with a force of magnitude 150 N. The box moves along the floor with a constant acceleration in the same direction as the applied force. Which statement is more precise regarding the magnitude of the kinetic friction force acting on the crate? a. It is greater than 150 N. b. It is equal to 150 N. c. The friction force must be zero. d. The kinetic friction force is constantly decreasing. e. It is less than 150N.