Final answer:
Different speed limits for objects of different masses are necessary because heavier objects require longer stopping distances. Mass is a direct measure of an object's inertia, and heavier objects resist changes in their motion more than lighter ones, affecting how quickly they can stop.
Step-by-step explanation:
The question pertains to why there are different speed limits for objects of different masses. The correct reason is that objects with greater mass require longer stopping distances. This is based on the principle that, for a given acceleration, a car that is going twice as fast does not stop in twice the distance—it travels much further before it can come to a stop. Hence, heavier objects, having more momentum due to their greater mass, will take a longer distance and time to stop compared to lighter objects at the same speed. This is reflected in traffic laws where heavier vehicles often have lower speed limits precisely because of the increased stopping distance required.
Mass is fundamentally a measure of the inertia of an object, which influences how much an object resists changes in motion. All else being equal, a heavier object (greater mass) will resist changes to its motion more than a lighter one (less mass). As a result, if two objects are traveling at the same velocity, the object with more mass will have greater momentum, requiring more force to change its motion, such as bringing it to a stop.
Therefore, in areas where quick stops may be necessary, such as near schools or in heavy pedestrian traffic areas, lower speed limits are often set for heavier vehicles to ensure safety and reduce the risk of accidents.