Even when you are driving at a constant 60 miles-per-hour along a straight, level road, your car's engine must be running. As the engine turns the car's wheels, friction between the ground and the tires exerts a forward force on the car. The car needs this forward force from the ground because
A)	air drag (air resistance) exerts a backward force on the car.
B)	an object that is moving requires a net force to keep it moving. In the absence of any net force, objects are motionless.
C)	an object's velocity points in the direction of the net force on that object.
D)	the car has a velocity and is thus accelerating. In order to accelerate, the car must be experiencing a net force.
Answer:A
Even when you are driving at a constant 60 miles-per-hour along a straight, level road, your car's engine must be running. As the engine turns the car's wheels, friction between the ground and the tires exerts a forward force on the car. The car needs this forward force from the ground because
A)	air drag (air resistance) exerts a backward force on the car. B)	an object that is moving requires a net force to keep it moving. In the absence of any net force, objects are motionless. C)	an object's velocity points in the direction of the net force on that object. D)	the car has a velocity and is thus accelerating. In order to accelerate, the car must be experiencing a net force.