Internal and External Forces

Newton's first law states that a net external force causes a change in motion. External forces act on an object or system, originating outside of the object or system. In contrast, internal forces originate inside the system of interest and do not lead to any acceleration. In simpler words, internal forces are forces that act on one part of an o...

What makes a car accelerate from rest?

Is it the force of the car's engine on the drive shaft or the force of its axles on the wheels? Or, is it the frictional force of the road on the car's wheels?

The drive shaft translates the internal force of the engine to the axles. The axles then rotate the wheels. The rotating wheels experi...