Question #44df8

1 Answer
Mar 12, 2017


The colliding car and insect really do exert equal #and opposite# forces on each other momentarily.


While the car is moving along towards the point of impact, the engine is working against air resistance, the friction of the wheels and axels, and losses in the transmission and motor in order to keep the vehicle moving.

It may be moving at a constant velocity or accelerating or braking at the time. The energy expended by the car at this time is #E#.
Any of the actions above require a huge magnitude of energy compared to that needed by the insect to maintain its flight.

But it is exactly the flight energy #fe# of the bug that the car will exert on it at the first moment of collision. As the collision proceeds, the car will need to exert enough further energy #fc# to compress the insect to a nearly flat residue. This energy will be matched by the insect as its body sequentially flattens.

So at the time the collision takes place, the total energy needed by the car to maintain its motion will be #E + fe + fc#.

The resultant change in energy from #E# will be so infinitesimal the operation of the car will be essentially unchanged.