If a moving car hits an object, the car will either decrease its acceleration or it will stop entierly, which we call the first collision. The car hits the object with some force and the object exeerts the the same force in the opposite direction. The people inside the car have been moving at the same speed as the car, so they will eventually hit the insides of the car, which is the second collision.The persons exerts a force on the car and the car exerts equal and opposite force to the persons. The interior body parts of the persons have also been moving at the same speed as the car and the body and will also be stopped by hitting the inside of the body of the persons, which is the third collision. The interior body parts hit the inside walls of the body while the body exerts the same force on the organs.Newton's First law of Motion states that an object continues to move or stay at rest until an outside force acts upon it, which changes its position. Newton's Third laws stat!
             es that for every force there is a equal and opposite reaction force. The reaction force has the same magnitude and acts in the opposite direction. The two forces act on diffrent objects and do not cancel one another. Only forces acting on the same object can be added together.
             ------------------------------------------------------------------------
             Eisenkraft, A. (1998). Active Physics. p 69
             ...