Question

When you step on the accelerator to increase the speed of your car, the force that accelerates the car is: A. the force of your foot on the accelerator B. the force of friction of the road on the tires C. the force of the engine on the drive shaft D. the normal force of the road on the tires E. none of the above

Answer 1

Answer:

B. the force of friction of the road on the tires

Explanation:

Unless the car engine is like jet engine, the main force that accelerates the car forward is the force of friction of the road on the tires, which is ultimately driven by the force of engine on the tires shaft. As the engine, and the shaft are part of the system, their interaction is internal. According to Newton laws of motion, the acceleration needs external force, in this case it's the friction of the road on the tires.