So a car moves, because the wheels exert a force on the ground which exert an opposite force back on the wheels causing it to move forward. The car then exerts this force on the air and the air back onto the car. Shouldn’t the resulting force on the car be 0 Newton then? Because the force the ground exerts on the car is the same as the force the air exerts on the car, thus cancelling each ofher out?
In: 0
> the wheels exert a force on the ground which exert an opposite force back on the wheels
Correct.
>The car then exerts this force on the air and the air back onto the car
Not completely. The car doesn’t exert “this” force (the one between tires and road) on the air. The aerodynamic drag (the resisting force that the air exerts on the car) depends on aerodynamic drag coefficient, front section of the car and speed. It does not directly depend on how strong the tires “push” on the ground. When you accelerate, the wheel force is bigger than the air force. Accordingly, you can’t say:
> the force the ground exerts on the car is the same as the force the air exerts on the car
There is however a specific situation where the first law applies: at constant speed. This situation is achieved by having the wheels and the ground exerting the same force on each other as the car’s body and the air.
Latest Answers