Final answer:
A gradual decrease in acceleration reduces the force exerted during a crash, keeping passengers safer. Cars with crumple zones increase the time of impact in a crash, which helps to dissipate energy and reduce injuries.
Step-by-step explanation:
A gradual decrease in acceleration decreases the force. Less force on the car keeps the people inside the car safer. The correct answer is a) gradual.
Cars have crumple zones that are designed to absorb the energy of the impact during a crash. This is beneficial because it reduces injury to the passengers by increasing the time of impact, which is answer a. The longer time of impact means that the force experienced by the passengers is spread out over a longer period, reducing the peak force and thus reducing the likelihood and severity of injuries.
An increase in applied force will cause an increase in acceleration if the mass is constant. This makes sense when we consider Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.