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)	an object that is moving requires a net force to keep it moving. In the absence of any net force, objects are motionless.
B)	air drag (air resistance) exerts a backward force on the car.
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:B
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)	an object that is moving requires a net force to keep it moving. In the absence of any net force, objects are motionless. B)	air drag (air resistance) exerts a backward force on the car. 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.