Question

A 4.0-kg object is moving across a ​friction-free​ surface​ with a constant velocity of 2 m/s. Which one of the following horizontal forces is necessary to maintain this state of motion?

a. 0 N
b. .5 N
c. 2.0 N
d. 8.0 N
e. depends on speed

Answer 1

The correct answer is (a) 0 N.

Since the object is moving with a constant velocity, its acceleration is zero. According to Newton's second law of motion, the net force acting on the object is equal to its mass multiplied by its acceleration (F=ma). Since the acceleration is zero, the net force must also be zero. Therefore, no horizontal force is necessary to maintain the state of motion of the object.