An object with a constant net force will have a constant speed.

A refrigerator is pushed across a floor, to the east, at a constant speed. Draw a vector to represent the direction of the net force acting on the refrigerator. If the net force is zero, state that explicitly. Explain your answer.

The net force is zero. Since the refrigerator is traveling at a constant speed in a straight line (to the east), its velocity is contant and its acceleration must be zero. Since the acceleration is zero, the net force must also be zero.

A refrigerator is pushed across the floor, to the east, with a constant net force, also directed to the east. Which of the following best describes the motion of the refrigerator? Explain your choice.

a. It slows down as it moves across the floor.

b. It travels at a constant speed across the floor.

c. It speeds up as it moves across the floor.

d. Can't be answered without more information about the force/refrigerator.

C is the correct choice. Since the refrigerator is experiencing a net force in the direction of its motion, it will be accelerating in that direction. Acceleration in the same direction as the velocity means an increase in the speed of the object.

A refrigerator is pushed across the floor, to the east, such that it speeds up by 1 cm/s each second as it moves. Which of the following best describes the net force acting on the refrigerator? Explain your choice.

a. It is increasing.

b. It is constant.

c. It is decreasing.

d..Can't be answered without more information about the force/refrigerator.

B is the correct choice. Since the refrigerator accelerates at a constant rate (1 cm/s/s) the net force must also be constant.