Final answer:
The bus continues moving when a firefly hits the windshield because the mass of the bus is much greater, making the force exerted by the firefly negligible. The concept of impulse indicates the small force has minimal impact on the bus's momentum.
Step-by-step explanation:
When an unfortunate firefly splatters against the windshield of a moving bus, the bus continues moving because the firefly exerts a very small force compared to the mass of the bus. According to Newton's third law, for every action, there is an equal and opposite reaction. However, the force the firefly can exert is negligible compared to the mass and velocity of the bus. Therefore, the bus hardly slows down. Understanding the concept of impulse, which is the product of the net force and the time over which it acts, can explain why a bus continues to move despite the collision.
The momentum change for the firefly is significant because of its small mass, leading to a potentially damaging outcome for the firefly. On the other hand, the change in momentum for the bus is practically zero, as the bus's mass is much larger, so it continues moving with little to no change in its velocity. This relates to the principle that a very large object will experience a much smaller change in velocity when a much smaller object exerts a force upon it.