this is just out of curiousity lol

lets say you're sitting in the passenger seat of your friend's car and ya'll are at a stop light. You see a fly hovering over the center console. Its not moving forwards, backwards, up, nor down but its just hovering over the center console. When the light turns green and your friend floors the car, you will feel the acceleration of the car and you will feel the force of the seat pushing up against you. Will the fly feel the force and will be thrown up against the back window? or will it just hover at the same place as if the car is still sitting? This has been troubling me for quite some time now.... anyone wanna explain what will happen?

2/22/2007 7:42:23 PM

Study Hall?

2/22/2007 7:46:07 PM

The fly would be thrown back i think, at least some. The reason you don't get thrown to the back window is that the seat is applying a force to you in the forward direction when the car accelerates.

2/22/2007 7:58:06 PM

^^ fine....someone move me to Chit Chat or something then

2/22/2007 7:59:25 PM

yo this exam just went right over my head

2/22/2007 8:02:28 PM

what? you can't read the mind of a fly and know what it will decide to do in a given situation?

2/22/2007 8:12:35 PM

The fly will hover in the same place.

2/22/2007 8:56:53 PM

The fly will just disappear into some transverse dimension

2/22/2007 9:05:34 PM

wow..... did you really just ask that question??? The fly won't feel any force (other than the aerodynamic ones in the car) that will move it anywhere. It'll slam against the back window unless it flies somewhere.


Stand on top of the car and jump just before your friend drives away... it's the same Idea (if you're honestly going to do it you should prolly use a skateboard)


Also, take PY205

2/22/2007 9:38:27 PM

Quote :

"The fly won't feel any force (other than the aerodynamic ones in the car) that will move it anywhere. It'll slam against the back window unless it flies somewhere."

[no]

2/22/2007 9:49:01 PM

BUT WHAT IF THE CAR IS ON A CONVEYOR BELT THAT IS MOVING IN THE OPPOSITE DIRECTION AT THE SAME SPEED? WILL THE CAR TAKE OFF?

but seriously: the air in the car is being accelerated and will move the fly with it, to a passengers frame of reference the fly may move a little but isnt going to stay in the same position (with respect to an external frame of reference) and hit the back glass

2/22/2007 9:49:49 PM

[yes]

[Edited on February 22, 2007 at 9:58 PM. Reason : ^^^ You need a new screen name]

2/22/2007 9:57:42 PM

think of it like this:

you just bought a goldfish and are bringing it home from the store in its bowl. when you pull out of your parking spot does the goldfish smack against the side of the bowl? no, the water is moving too.

2/22/2007 10:20:52 PM

what if the windows are down in the gold fish bowl? HUH? WHAT THEN!

2/22/2007 10:30:03 PM

If you are in a helicopter hovering for a long time, the earth does not rotate beneath you as if it was independent of you.

Assuming the car (and the air inside it) is a closed system, the fly will not move.

2/22/2007 10:37:13 PM

Yea... but how much is the air in the car gonna move... I think when you're going THAT indepth into the problem the answer is who knows b/c you can't predict that airflow, I'm pretty confident that noone posting on this board is proficient enough in CFD to work this problem.

A Tanzarian...you're a moron, call me when you graduate with an Engineering degree




[Edited on February 22, 2007 at 10:44 PM. Reason : .]

2/22/2007 10:39:37 PM

Quote :

"but how much is the air in the car gonna move..."

The air isn't going to move (not much anyway). Do you feel a breeze inside the car whenever you start moving? When the car starts moving it carries everything in it--the passengers, the air, the fly--along with it.

Quote :

"A Tanzarian...you're a moron, call me when you graduate with an Engineering degree"

OHHHHHHHHHHHHHHHHHHHHH!!!!!!! youz gots more smartz than me cuz yous done gaduated already

Last resort of someone who doesn't know what the fuck they're talking about: But I have a degree!

The fact that you have an engineering degree is an embarrassment to COE.

2/22/2007 10:54:33 PM

Prove that the air in the car doesn't move.

2/22/2007 11:13:15 PM

Quote :

"The air isn't going to move (not much anyway)"

prove that the fly will "slam against the back window unless it flies somewhere."

2/22/2007 11:15:18 PM

You could probably catch a fly and put it in your car and try it before anyone here agrees on an answer.

2/22/2007 11:19:16 PM

umm, wizzkidd is right. you must be trollin Tanza.

Simple experiment: Toss a penny in the air (inside the car). Punch the accelerator and watch the penny move backwards relative to you. The higher the rate of acceleration and the higher the toss will result in more relative motion--watch where the penny lands. You have to be in accelerated motion. If you toss the penny traveling in steady state then the penny is traveling at the same speed as you (zero relative velocity).


The "goldfish in the bowl" or "penny in a jar full of maple syrup" is different because of the fluid properties of the medium (viscosity,density). Why is a tsunami or a mud slide, moving at fairly slow velocity, MUCH more devastating than a wind blown at the same seed? Answer: Density.

The car moves you forward because the seats are solid. But have you noticed that your body can "feel" acceleration. Have you ever been on a roller coaster and felt that acceleration. That's because your internal organs are moving around inside you. Your body interprets this as acceleration.

Have you ever accelerated so fast in a car that your head is thrown against the back of the seat? Or have you ever decelerated so fast(e.g. a car crash) that your head gets thrown forward? Where is the air there??? why isn't the air preventing your head from moving forward? I mean the system is stll closed right?


More than likely the fly will stay in the same place, not because the air is transporting him, but rather because the fly has amazing visual sensory/visuo-motor system and reacts to changes in it's environment at equally amazing speeds. This is a current research topic in aerospace; modeling how the fly processes it's visual information of it's surroundings and turn that into a control law via wide field integration.

[Edited on February 23, 2007 at 9:07 AM. Reason : .er]

[Edited on February 23, 2007 at 9:10 AM. Reason : blah]

2/23/2007 8:51:25 AM

:hand on forehead:

2/23/2007 10:47:55 AM

i swear, there are some fucking morons on this website

2/23/2007 11:24:26 AM

Balance a raw egg on the dashboard, then tell your friend to floor it.

"When the car starts moving it carries everything in it--the passengers, the air, the fly, the egg --along with it." Give it a try.

2/23/2007 2:28:51 PM

^

^^^ My sentiments exactly.

^^^^ You realize that air has mass and that it does act on other objects, right? It even acts on your body, however, due to your mass, it's usually negligible compared to other forces. Nonetheless, it does act on you and things like running outside require more effort than running inside on a treadmill.

The difference between your body and the fly is mass. A fly is very light weight (a few milligrams) and even a penny has several hundred times the mass of a fly. Hell, the mass of the air inside your car is greater than that of a fly. So, while the effects of air inside your car may be negligible when it comes to you or to pennies, it is not negligible with respect to low mass objects such as a fly.

2/23/2007 2:37:49 PM

Quote :

"You realize that air has mass and that it does act on other objects, right? It even acts on your body, however, due to your mass, it's usually negligible compared to other forces. Nonetheless, it does act on you and things like running outside require more effort than running inside on a treadmill."

are you trying to say there is no air in my house!?!

2/23/2007 4:42:43 PM

I'm not sure how you got that from that quote...............

2/23/2007 5:20:35 PM

^^^true. I was speaking to the stupid ass comment about the goldfish in water. Anyway, I understand your point, but try this experiment. Take a very light down feather from a pillow release it in the car and hit the gas. My suspension is that you will see a change in the relative velocity.

My point being that while there is some truth to your point, the feather and other objects are passive. Whereas a fly has an active control system that adjust at amazing speeds. Flies interpret their surroundings and "measures" change in the environment and adjust accordingly.

This goes back to the stupid helicopter and earth rotation example, who the fuck comes up with these retarded ideas.

Quote :

"i swear, there are some fucking morons on this website"

2/23/2007 5:28:56 PM

what about a bee in an elevator??

2/23/2007 7:05:00 PM

the goldfish in the bowl is a good analogy. obviously, as an analogy, it is simply a loose comparison for explanation and not a direct similarity. the water in the bowl is acting on the fish in the same way as the air is on the fly, feel free to respond about how this is stupid because it has a higher viscosity but you are missing the point that its just a fucking analogy.

the air inside the car is going to swish some and the fly very well may be moving against that to stay absolutely still, but if the fly were to just chill out its going to move along with the air. this is really easy to demonstrate with a feather, i actually tried it on my way to work this morning with a feather from my down comforter that was stuck to my shirt. amazingly the feather did not end up against the back glass.

the concepts here should all be mind blowingly obvious, but as i learned with the plane on the conveyor belt thread a lot of you are mind blowingly retarded.

2/23/2007 7:14:43 PM

The fly will stay in one place.

2/23/2007 7:23:32 PM

haha

relative to what?

2/23/2007 8:01:25 PM

BUT WHAT IF THE FLY IS IN A JAR, WILL THE JAR WEIGH THE SAME?

2/23/2007 8:30:16 PM

^ WHAT?!?

2/23/2007 11:21:20 PM

dude

we've taken py205 too

a long, long time ago

you aren't blowing anyone's mind here

go away

2/24/2007 9:30:27 AM

Lets put the fly in a vacuum, then consider the same question.

2/24/2007 10:01:27 AM

SPLAT!

2/24/2007 10:25:32 AM

Okay, what if the fly were wearing roller skates and on a conveyor belt?

Would the fly move???!?!!?????

2/24/2007 10:26:26 AM

Only if the fly is doing the Hokey Pokey at the time.

2/24/2007 10:32:50 AM

WHAT IF SLED DOGS WERE PULLING THE FLY AND IT WAS ON ICE?

2/24/2007 8:23:28 PM

2/24/2007 9:00:27 PM

how about this: fly+sled dogs+roller skates+conveyor belt=??????

2/25/2007 1:27:32 AM

damn

2/25/2007 3:09:01 AM

^ my thoughts exactly

2/25/2007 6:40:46 PM

Quote :

"Will the fly feel the force and will be thrown up against the back window? or will it just hover at the same place as if the car is still sitting?"

You seemed confused. Staying in one place relative to car while it accelerates would require a significant force, not the other way around. If there was no force, the fly would hit the back window or rather the back window would hit the fly.

The air is going to apply force to the fly. Will this be exactly enough force to keep the fly in place? Who the fuck knows?

2/26/2007 9:45:45 AM