91Ó°ÊÓ

A body accelerates when a net force acts on it and travels in the same direction as the net force. The product of mass and acceleration vector is equal to the force vector.

$∑\stackrel{→}{\mathrm{F}}=\mathrm{m}\stackrel{→}{\mathrm{a}}$

A moving car can slow down on a level highway because of drag and frictional forces. The force that opposes an object's motion caused by the fluid the object moves is called drag force. And friction is the opposing force acting between two objects where they are in contact.On the car, the drag force is due to the air, and friction is between tires and the road, which can cause the car to slow down.

When the car accelerator is pushed down, the engine exerts a torque on the tires, which exerts a driving force onto the car.

Thus, the drag force is due to the air and friction between tires and the road, which can cause the car to slow down. When the car accelerator is pushed down, the engine exerts a torque on the tires, pushing the car forward.