1. The problem statement, all variables and given/known data This question goes like this: In an accident involving a big lorry and small car, the drivers of both vehicles were seriously injured. A student made a remark about the accident as follows: "A big lorry and a small car moved in the opposite directions and made a head-on collision. By Newton's third law of motion, the forces acting on both drivers are the same. As a result, both drivers were seriously injured." Comment on the student's remark. 2. Relevant equations [F][/net]=ma Third law: Whenever an object A exerts a force on another object B, B exerts a force of equal magnitude and opposite direction on A at the same time. 3. The attempt at a solution I think the student is correct. As the two vehicles collide head-on, they form an action-and-reaction pair. Therefore, both the lorry and the car receive the same magnitude of force exerted on them by each other. What I'm not so sure about is which force caused the drivers' injury? Is it because: the cars receive forces from opposite directions and this force causes the cars to stop abruptly, while the drivers still tend to move forward due to inertia. As a result, they hit the windscreens and get injured? Like the teacher said this question is not that easy so I'm quite uncertain about my answer.