Final answer:
Correct option: b) The car and d) The truck.
In a head-on collision where no external forces act and both vehicles stick together, both the small car and the large truck experience the same magnitude of momentum change, as the law of conservation of momentum dictates that momentum is conserved in a closed system.
Step-by-step explanation:
When a collision occurs between two objects, such as a small car and a large truck sticking together after colliding head-on, the law of conservation of momentum tells us that the total momentum of the system (car and truck together) before the collision is equal to the total momentum of the system after the collision, provided no external forces are acting on it. Thus, both the car and the truck will experience the same magnitude of momentum change, but in opposite directions, as a result of the collision.
The momentum change experienced by any individual object in a collision can be calculated by the difference in its momentum before and after the collision. If we consider the system of both the car and the truck, since they stick together and move with the same final velocity, their momentum changes will be equal in magnitude (but of opposite direction since one vehicle slows down while the other is accelerated by the collision). This is because momentum is a vector quantity, and in a closed system (with no external forces), momentum is conserved.