If a fly is within a moving vehicle, how come it can hover in the vehicle instead of keeping up with it?

Question

Ok, let's say you're driving down the road in your car, and there's a fly in the car that's just kinda flying around the same general little area. How come the fly doesn't have to keep flying forward in order to keep up with the vehicle? Wouldn't the fly eventually be hit by the back of the vehicle?

Answer 1

The fly is flying in the air in the vehicle, which is moving with the vehicle. Under constant velocity the air is steady in the vehicle.


Here's something rather counter-intuitive:
If you place a balloon in a vehicle and let it float, then accelerate the vehicle, the balloon will move toward the front of the vehicle. The reason is the balloon is floating in the air, which means its mass downward force is being countered by the upward force of its' bouyancy. When the car accelerates, the back of the car pushes against the air at the back, which increases the pressure at the rear of the vehicle. The increased air pressure at the rear of the vehicle will push more on the balloon than the lower air pressure at the front of the vehicle, which will cause the balloon to move forward. Note this works only while tthe car is accelerating, not under a constant velocity.

Answer 2

If the fly starts in the car, then it has the same velocity as the car relative to the ground. So for the fly, it's like just flying around outside. It's the same reason when you're on a train you don't have to constantly run to stay on it.

Answer 3

The fly is moving relative to the air inside the vehicle. The air inside the vehicle is moving at the same speed as the vehicle.

Answer 4

The fly and the vehicle have a mutual velosity

Answer 5

b/c the wind (aerodynamics) is going around the outside of the vehicle. Put your window down.

Answer 6

No. For the same reason you don't have any problem keeping up with your car.