Physics? A fly in a car.?

Question

If your car is stopped at a red light and there is a fly in you car flying around right by your rear view mirror and then you take off does the fly shoot towards the back of the car or continue to fly in the front of the vehicle. This is my friends question and he has asked teacher and no one knows the answer.

Answer 1

The bug is flying in the air contained within the car. From the bug's perspective, it is a closed system. He won't be affected by the car moving in any direction as long as the car isn't approaching the speed of light. *laughter*

Answer 2

If the windows of the car are closed, then the car is an isolated environment. To a certain extent, air will be displaced by momentum, but not significantly, and the fly will probably not notice much.

If the windows of the car are open, there will be more air coming in as you move forward, because the car separates the stream of the air and creates pressure at its surface. The window allows the pressure to push air into the car, and there will be considerable wind from the front to the back of the car, which will definitely affect the fly.

You can experiment by driving with a friend blowing bubbles. Try mixing some Elmer's glue into the bubble solution to make the bubbles stronger, and only crack the window, or the bubbles will break before they can move much.

Another cool experiment is to have a loose helium filled balloon in the car. Being lighter than air, it constantly moves toward the front of the car, rather like my father's dog, which was apparently convinced it could drive, as it tried to get into the front seat with me.

Answer 3

The fly has a mass denser than air. As the car accelerates forward, the fly's inertia tends to keep him stationary, and he would appear to be moving toward the back of the car, unless he really picked up his wing strokes.

The opposite would be true if you had a Helium balloon in the car. As the car accelerated, the air, being less dense than the Helium in the balloon would move toward the back of the car and force the Helium balloon forward into the front windshield.

Answer 4

Nope, the fly stays in the same place because all the air in the car is moving with the car.

Want to really stump your teacher? Ask him/her this:

Say there is a large bird in your car that weighs (pick a number) 2 pounds and he is sitting on the seat...your car is now 2 pounds heavier because of the bird. Now, say that bird takes off and flys in the car and is not touching anything...is the car still 2 pounds heavier because of the bird in it?


The answer: YES! In physics, for every action there is an equal and opposite reaction. This means that for a 2 pound bird to hover in the air it requires 2 pounds of thrust (air going downward from the wings) to level out. This air pushing down from the birds wings that enable it to fly pushes down on the car as well. It is the exact same weight as the bird sitting on the chair.

Answer 5

A moving object will have it's speed and the speed of the car combined.The only thing is you will have to factor in how much the windshield affects the fly and it can affect it 100%.


Watch this video of a pitching machine in the back of a truck firing a ball 100mph in the opposite direction of the truck going 100mph and the ball drops straight down. 100-100=0

http://www.japanprobe.com/?p=1913

Answer 6

Shoots towards the back.