1st law - law of inertia. An object at rest will tend to remain at rest and an object in motion will tend to remain in motion with constant speed if there is no net force acting upon it.
2nd law - F = ma. The force applied on an object by another object is proportional to the mass and acceleration.
3rd law - Any action force always has an equal and opposite reaction force.
The cars would continue to be at rest or in motion with constant speed if no net forces were acting up on them (i.e. the crash, friction). Since the force applied in the crash is proportional to the mass of the impacting car(s), the greater the mass of the impacting car(s), the greater the force applied, and therefore the greater the destruction. The smaller the mass of the impacting car(s), the less force is applied, and the destruction would be less. When the impacting car collided with the other car and applied a force, the car that was smashed into applied a reaction force with equal magnitude back onto the impacting car. Because a force is being applied to both the impacting car and the recieving car, both cars take damage.
