Question

The net force on a car is zero in both the horizontal and vertical directions which two situations could be true about the motion of the car

Answer 1

Two possible situations:

- The car is at rest. In this case, there are only 2 forces acting on the car, both in the vertical direction: the weigth of the car (downward) and the normal reaction of the asphalt on the car (upward). The two forces are equal in magnitude but in opposite directions, so the net force is zero.

- The car is traveling at constant velocity. In this case, there are 4 forces: in the vertical direction, as before, we have the weigth of the car (downward) and the normal reaction of the asphalt on the car (upward). The two forces are equal in magnitude but in opposite directions, so the net force in the vertical direction is zero. However, this time the car is also moving, so there are forces acting along the horizontal direction: the driving force, which pushes the car forward, and the frictional force, which goes in the opposite direction. Since the car is moving at constant velocity, its acceleration is zero, so the net force must be zero: therefore, the magnitude of these two forces is equal.

Answer 2

Since both the net force of the horizontal and vertical directions on the car is zero, we can imply that it is in equilibrium in two cases: either it is at rest, or it is moving on a constant velocity. I hope my answer has come to your help. God bless and have a nice day ahead!