Anyone know why a fly (or anyother flying insect) doesn’t splatter on your rear windshield while it is hovering around inside your car while you are doing 75 mph. How can they tell or what causes them to be able to know that the vehicle is moving? Or is it just something to do with physics that I have no idea about?
Dude, the air in your car is moving with the car; the fly is flying in the air.
The better question is why don’t they splatter when you suddenly stop? I guess that it’s the pressure waves in the air, and the fact that you don’t really stop all that suddenly, on the fly scale of time.
They are airborne. The air they’re flying in is going 75 mph along with everything else in the car, so they don’t hit the rear window for the same reason that you don’t.
Just because you’re going 75 mph doesn’t mean that the air in your car is going back at 75 mph. Does it feel like it is to you?
Pretty much for the same reason that riding in a closed car at 75mph feels a lot different to you than riding in a car with no roof, side windows or windshield at 75mph. As long as the car isn’t changing its speed or direction in any way, the physics inside the moving, closed car will be exactly the same as the physics in your living room at home.
Nametag, for the fly to splatter against the inside of the glass when braking, you’d have to stop quickly enough for you to splatter against the windshield as well. Even then, a fly’s body is subject to greater air resistance than a human’s, so it would probably survive a faster deceleration than you would.
An interesting question I was asked during a college interview: You have a helium-filled balloon inside a car. The car then accelerates. Assuming no friction against the walls and roof of the car, which way will the baloon move, relative to the direction of acceleration?
[hijack]
Forwards? (I’m assuming it’s a trick question.)
I’m so glad someone figured out how to word this question because i have been wanting to post it for sometime. Thanks ** OuR12_? **.
The balloon would attempt to remain staionary and then it would go with the car, therefore moving in the direction of the acceleration ultimately, right?
Nope.
Because of air pressure differences within the compartment, when you accelerate the balloon will forced forward relative to the compartment (The air is squeezed towards the back, making it heavier than the air towards the front. The baloon, wanting to head towards air of lighter density, makes its way forward). Likewise, when you turn to the left, instead of the balloon moving to the right, like you think it would, it will move to the left (Again, it will move towards the area of least air pressure).
It basically does the opposite of what you’d think.
I win!
A more complete answer would be that the air, the fly and all the stuff in side the car is in the same intertial frame of reference as the moving car. If the car were moving in a perfectly straight line at a constant rate and you ignored clues like wind and tire noise and had blackout windows there are few simple experiments which would tell you if you were moving or stopped. Of course a car on the earth isn’t travelling in a straight line so a gyroscope might provide a clue.