Which answer make more sense to you?
One answer: Inside the vehicle the insect has already attained the velocity of the car. It need not do anything to move at that speed. When it need to fly one or two meters to reach the front panel of your car it just need to fly this distance in its normal speed. (In effect the velocity of the insect at that time is the velocity of the car + the speed of the insect flying). Suppose you carry an orange in your hand while travelling in a bullet train at 200 miles per hour the orange also gained the same velocity. If you hold the orange in your hand and just drop it down it will fall near your legs. But imagine a person standing outside the train and seeing only the orange as you drop it. He will see an orange that fly in the air at the speed of 200 miles per hour and slowly descending! | Second answer: Frames of References. A mosquito buzzing around in a plane that is flying at near-about constant speed and direction (thus velocity is almost unchanging) is relatively safe. This happens because the mosquito when it entered the plane before take off, DID get jerked backwards when the plane accelerated off the runway. But that acceleration probably didn't make it smash into the the back of the plane. I would assume that in that time the mosquito sought some support of a wall to avoid being thrown backwards violently. But after the plane took off the mosquito was ALSO now travelling in the view of an observer outside the plane on the ground with the same velocity as the plane. Remember, it also accelerated forwards when it was on the wall! So the mosquito essentially moved from a frame of reference of the ground based observer into the frame of reference of the plane due to the acceleration. This is of course from its own point of view. So the answer to your other question: Which force is preventing the mosquito from jerking back?: It is inertia, provided by the first law of motion and the state of the mosquito, velocity, maintained by the second law of motion. Inertia is not a force per se or rather not a force we know a clear origin of, but it is an observation of the nature that things that are once set in motion will not by themselves experience force unless an EXTERNAL influence acts on the mosquito. Just to point out the particulars of the directions of travel do not contribute a lot to the scenario. |