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Posted: 10/11/2004 5:00:23 AM EST
I understand that if you are traveling in a car at 60 mph and holding a ball when you toss it in the air it does not go flying back to the rear of the car because it is also traveling at 60mph.

How come a fly can fly around inside a car that is traveling at 60 mph? It would seem to me that the fly who is flying is independent of the car and would not have the forward momentum of the car. You would think that when it first took off in the car that it would be fine, but would loose it's momentum pretty fast and would slam against the rear windshield. But tell that to the damn fly who was doing circles around my head while I was driving down the highway this weekend.

This has been driving me crazy for years, I hope someone can answer this.
Link Posted: 10/11/2004 5:02:32 AM EST
[Last Edit: 10/11/2004 5:03:45 AM EST by torstin]
the fly is no different than the ball.
Link Posted: 10/11/2004 5:03:22 AM EST
Well, I can think of two things.

If the fly is perched on a surface in the car when it stars moving, then it accelerates same as the car.

When it takes off and flies, it has the initial speed, PLUS it's flying through a medium that is ALSO moving at the speed of the car (the air inside the car). Minor fluctuations between the fly, the car, and the fluidity of the air in the car become almost impossible to measure because the fly is flying around so erratically as a natural act.

It's the best I can think of...
Link Posted: 10/11/2004 5:03:37 AM EST

Originally Posted By wedge1082:
This has been driving me crazy for years, I hope someone can answer this.



Short drive???
Link Posted: 10/11/2004 5:05:50 AM EST
But the ball comes down quickly. The fly can fly around for a long time. Would it not loose its velocity that it got from the car pretty quick?
Link Posted: 10/11/2004 5:06:08 AM EST
The resistance of the air limits the fly's speed.



Samuel
Link Posted: 10/11/2004 5:07:40 AM EST
its a point of view problem.

Looking at your car from the outside: the fly, you, the air in the car, and the car itself are all going 60mph.

if the fly is moving inside the car from back to front he's going slightly faster than 60mph

if the fly is moving inside the car from front to back he's going stightly slower than 60mph

When you change your point of view to inside the car you just subtract 60mph from everything.



Link Posted: 10/11/2004 5:07:46 AM EST

Originally Posted By wedge1082:
But the ball comes down quickly. The fly can fly around for a long time. Would it not loose its velocity that it got from the car pretty quick?



Remember, the act of flying is caused by the fly exerting force upon the air in the car. The ball has no such force. If the fly stops beating its wings, it'll go ballistic just like the ball.
Link Posted: 10/11/2004 5:08:08 AM EST

Originally Posted By wedge1082:
I understand that if you are traveling in a car at 60 mph and holding a ball when you toss it in the air it does not go flying back to the rear of the car because it is also traveling at 60mph.

How come a fly can fly around inside a car that is traveling at 60 mph? It would seem to me that the fly who is flying is independent of the car and would not have the forward momentum of the car. You would think that when it first took off in the car that it would be fine, but would loose it's momentum pretty fast and would slam against the rear windshield. But tell that to the damn fly who was doing circles around my head while I was driving down the highway this weekend.

This has been driving me crazy for years, I hope someone can answer this.



The air inside the car is moving at the same speed as the car.
Link Posted: 10/11/2004 5:08:27 AM EST

Relativity.

The fly is not flying in relation to the
ground, but in relation to the car. Same
reason why if you jump in a downward
traveling elevator, you do not leviate.
Link Posted: 10/11/2004 5:08:51 AM EST
[Last Edit: 10/11/2004 5:10:22 AM EST by Dino]

Originally Posted By wedge1082:
But the ball comes down quickly. The fly can fly around for a long time. Would it not loose its velocity that it got from the car pretty quick?



the ball only has an impulse to keep it up.

the fly is being supported continually by its beating wings


its no different than tossing a ball in the air when your at zero velocity. It goes up and it comes down.

The same thing occurs when your in a vehicle moving at a constant speed.

Link Posted: 10/11/2004 5:09:34 AM EST
There is no fly...
Link Posted: 10/11/2004 5:10:14 AM EST
open the window and see if the fly can keep up
Link Posted: 10/11/2004 5:11:38 AM EST

Originally Posted By TheCynic:
Relativity.

The fly is not flying in relation to the
ground, but in relation to the car. Same
reason why if you jump in a downward
traveling elevator, you do not leviate.



you mean if I'm in a elevator that has a cable break and I jump right as I hit the ground it won't save me? damn I hate physics!

Link Posted: 10/11/2004 5:11:40 AM EST

Originally Posted By Dino:
its a point of view problem.

Looking at your car from the outside: the fly, you, the air in the car, and the car itself are all going 60mph.

if the fly is moving inside the car from back to front he's going slightly faster than 60mph

if the fly is moving inside the car from front to back he's going stightly slower than 60mph

When you change your point of view to inside the car you just subtract 60mph from everything.






So because the air in the car is also going the same speed everything in the car would act like it was just not moving at the speed of the car?
Link Posted: 10/11/2004 5:12:01 AM EST
Link Posted: 10/11/2004 5:15:31 AM EST

Originally Posted By anothergene:
The air in the car is travelling at 60 MPH, so the fly isn't affected, but if the fly were to be shooed out the window, I'm sure it would LOSE momentum rapidly as the speed of the car exceeds the flys top speed by a large margin.
I would like to see a slo-mo of how the fly copes with the transition from 60 to 3 MPH in a few seconds. He says whoa, I bet.



I bet he dies quickly.
Link Posted: 10/11/2004 5:15:52 AM EST


So because the air in the car is also going the same speed everything in the car would act like it was just not moving at the speed of the car?



Correct.

BTW, here's an interesting experiment...take a helium balloon with you in the car...when you brake sharply, the balloon will actually move to the REAR of the car instead of the front...freaky...
Link Posted: 10/11/2004 5:19:10 AM EST

Originally Posted By IamtheNRA:


So because the air in the car is also going the same speed everything in the car would act like it was just not moving at the speed of the car?



Correct.

BTW, here's an interesting experiment...take a helium balloon with you in the car...when you brake sharply, the balloon will actually move to the REAR of the car instead of the front...freaky...



Now why is that?
Link Posted: 10/11/2004 5:19:48 AM EST
[Last Edit: 10/11/2004 5:21:10 AM EST by Paul]
Link Posted: 10/11/2004 5:21:43 AM EST

Originally Posted By Paul:
You do understand that the planet is revolving at something close to 1000 miles an hour right?

If you want something in physics to really bug you look up "spooky action at a distance"

Quantum physics blows my tiny Netwonian mind.



I have thought about that too, but I attribute it to gravity.
Link Posted: 10/11/2004 5:23:39 AM EST
[Last Edit: 10/11/2004 5:26:08 AM EST by Boomholzer]
The medium around the fly i.e. the air in which the insect in flying in, is moving with the car. Therefore, the insect's flight is relative to the car and not the earth.

If the fly were light we could look it it as entraned ethr theory.

NEXT TIME you are traveling 60MPH, hock some phlem at the windshield in front of you, will it end up in your face or on your windshield?
Link Posted: 10/11/2004 5:23:59 AM EST

Originally Posted By wedge1082:
I understand that if you are traveling in a car at 60 mph and holding a ball when you toss it in the air it does not go flying back to the rear of the car because it is also traveling at 60mph.

How come a fly can fly around inside a car that is traveling at 60 mph? It would seem to me that the fly who is flying is independent of the car and would not have the forward momentum of the car. You would think that when it first took off in the car that it would be fine, but would loose it's momentum pretty fast and would slam against the rear windshield. But tell that to the damn fly who was doing circles around my head while I was driving down the highway this weekend.

This has been driving me crazy for years, I hope someone can answer this.




Take a shower.
Link Posted: 10/11/2004 5:25:30 AM EST
[Last Edit: 10/11/2004 5:26:54 AM EST by Admiral_Crunch]
The car is moving at a constant 60 mph, therefore there is nothing to push the bug to the rear, just as nothing is pushing you to the rear. Motion doesn't push you around. Acceleration does. If you are accelerating, then the fly would be pushed toward the rear, just as you would be pushed back into your seat. Of course, the fly can compensate for this force by flying forward.

(This, of course, assumes your windows are closed. If you have no windshield, then you are pushing through the air, and the air is resisting you, or "pushing back".)
Link Posted: 10/11/2004 5:25:55 AM EST
Newton's First Law of Motion:

Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

Objects inside the car are in this state of uniform motion until acted upon by an outside force. Objects on the surface of the earth are also in a state of uniform motion until acted upon by some other force. This really is not that difficult of a concept.

Then again, it may just be A TRAP!
Link Posted: 10/11/2004 5:28:42 AM EST


It's a FLYTRAP!

(Sorry.)
Link Posted: 10/11/2004 5:31:06 AM EST
[Last Edit: 10/11/2004 5:33:36 AM EST by ANGST]
Wedge, why does your X-wing fly like an airplane in space and make noise ?

Link Posted: 10/11/2004 5:31:11 AM EST
As several folks said, it's the air:

The air inside the car isn't moving 60 MPH relative to the car. It is pushed back a little because of its inertia, but then it recirculates. Otherwise, there would be a huge build-up of air in the back of the car and the driver would suffocate. :D This recirculation of air is not very fast; otherwise you would feel the breeze.

The ball, having a relatively high mass/cross section ratio, doesn't feel the effect of air resistance much, so it follows a ballistic path pretty well. Try the same experiment with a balloon; the result is considerably different.

The fly is able to exert force against the air. When you think about how fast flies can go, they are easily able to overcome any air currents in the car.
Link Posted: 10/11/2004 5:32:44 AM EST

Originally Posted By wedge1082:

Originally Posted By IamtheNRA:


So because the air in the car is also going the same speed everything in the car would act like it was just not moving at the speed of the car?



Correct.

BTW, here's an interesting experiment...take a helium balloon with you in the car...when you brake sharply, the balloon will actually move to the REAR of the car instead of the front...freaky...



Now why is that?

Sudden change in air pressure as the air in the car shifts towards the windshield as you slow. The pressure at the windshield is higher than the pressure at the back window. The helium balloon is more affected by the air pressure differential in the cabin of the vehicle than it is by momentum. This also works when you accelerate (opposite direction of air and balloon travel) but you can stop faster than you can accelerate, so the behavior is more pronounced when braking.

As to the fly, wait till that sucker's in the air, then lock up the brakes and watch him bounce off the inside of the windshield.
Link Posted: 10/11/2004 5:35:45 AM EST

Originally Posted By ANGST:
Wedge, why does your X-wing fly like an airplane in space and make noise ?





See, in the future, all spacecraft/spacesuits will have a common sound circuit that links everybody together (allies, foes, whatever). Without that, you couldn't hear the heart-stopping roar of Darth Vader's TIE fighter, or the firing of laser cannons. War just wouldn't be the same!
Link Posted: 10/11/2004 5:52:03 AM EST

Originally Posted By ANGST:
Wedge, why does your X-wing fly like an airplane in space and make noise ?

gsquadron.tripod.com/wedge3.jpg



The Force.
Link Posted: 10/11/2004 5:55:37 AM EST
From an old insurance claim:


Originally Posted By A Really Bad Driver:
In my attempt to kill a fly, I drove into a telephone pole.

Link Posted: 10/11/2004 6:04:08 AM EST

Originally Posted By CavVet:

Originally Posted By wedge1082:
This has been driving me crazy for years, I hope someone can answer this.



Short drive???



short bus!!!

Link Posted: 10/11/2004 6:05:53 AM EST

Originally Posted By wedge1082:
I understand that if you are traveling in a car at 60 mph and holding a ball when you toss it in the air it does not go flying back to the rear of the car because it is also traveling at 60mph.

How come a fly can fly around inside a car that is traveling at 60 mph? It would seem to me that the fly who is flying is independent of the car and would not have the forward momentum of the car. You would think that when it first took off in the car that it would be fine, but would loose it's momentum pretty fast and would slam against the rear windshield. But tell that to the damn fly who was doing circles around my head while I was driving down the highway this weekend.

This has been driving me crazy for years, I hope someone can answer this.



Open your windows. Bye Bye Fly
Link Posted: 10/11/2004 6:08:29 AM EST
I prefer it when I'm driving at 60mph and the fly gets in front of the car.... I wonder what that last thing to go through his mind was? Oh yeah. His butt.
Link Posted: 10/11/2004 7:18:27 AM EST
Are these flies coming from the Diaper Genie
Link Posted: 10/11/2004 7:28:43 AM EST
Link Posted: 10/11/2004 7:34:02 AM EST
ding ding ding!

We have a winner
Einstein's theory of relativity


Originally Posted By TheCynic:
Relativity.

The fly is not flying in relation to the
ground, but in relation to the car. Same
reason why if you jump in a downward
traveling elevator, you do not leviate.

Link Posted: 10/11/2004 7:38:12 AM EST

Originally Posted By keving67:
ding ding ding!

We have a winner
Einstein's theory of relativity


Originally Posted By TheCynic:
Relativity.

The fly is not flying in relation to the
ground, but in relation to the car. Same
reason why if you jump in a downward
traveling elevator, you do not leviate.




No, we don't.

The reason you don't levitate in a descending elevator is because your acceleration downward due to gravity is greater than the acceleration of the elevator (which is zero when the elevator is at top speed).

If the elevator was free-falling, you WOULD levitate, a-la the Vomit Comet.

Einstein's theory of relativity has much bigger fish to fry. Oh, and the fly IS moving in relation to the ground. If it's moving forward at 30 mph when the car is going 60mph, the fly is doing 90 mph in relation to the ground.
Link Posted: 10/11/2004 7:39:58 AM EST
The fly doesn't have any trouble moving about in a car for the same reason you don't have any trouble using a lavatory in an airplane. Would it make sense to expect that you couldn't walk up the aisle in an airplane?
Link Posted: 10/11/2004 7:41:51 AM EST
Link Posted: 10/11/2004 7:44:14 AM EST
Link Posted: 10/11/2004 7:59:31 AM EST

Originally Posted By wedge1082:
But the ball comes down quickly. The fly can fly around for a long time. Would it not loose its velocity that it got from the car pretty quick?



The fly is flying in the air inside the automobile. The air is traveling 60 mph with the automobile. You are driving, and, if the windows are up, the air feels still. The fly is moving at 61 mph relative to an observer standing alongside the road, but only seems to be moving past your head at 1 mph.

Now, if you rolled down your window, and the fly flew out that window, he would decelerate from 61mph to 1mph pretty fast.
Link Posted: 10/11/2004 8:02:37 AM EST

Originally Posted By IamtheNRA:

Originally Posted By wedge1082:
I understand that if you are traveling in a car at 60 mph and holding a ball when you toss it in the air it does not go flying back to the rear of the car because it is also traveling at 60mph.

How come a fly can fly around inside a car that is traveling at 60 mph? It would seem to me that the fly who is flying is independent of the car and would not have the forward momentum of the car. You would think that when it first took off in the car that it would be fine, but would loose it's momentum pretty fast and would slam against the rear windshield. But tell that to the damn fly who was doing circles around my head while I was driving down the highway this weekend.

This has been driving me crazy for years, I hope someone can answer this.



The air inside the car is moving at the same speed as the car.




Yeah, compare the fly in the air as a fish in a fishbowl on your lap. The fish doesn't slam against the back of the bowl, itjust sits there happily swin=mming around. Fluid is a fluid.
Link Posted: 10/11/2004 8:24:15 AM EST

Originally Posted By cmjohnson:

I've always wondered what would happen if you were to fly a spaceship at a few miles per hour less than the speed of light and then fire the ship's forward facing cannon. Its projectile wants to do maybe 3000 FPS more than the ship, but if that 3000 FPS were enough to take the projectile over the speed of light, what happens?

CJ



Depends on your frame of reference. According to the phisics teacher I had in college, this would not be possible. IF it was possible then the projectile would cease to exsist.

Kind of like if 2 ships were headed towards each other at .98 of the speed of light, is the closure rate then greater that the speed of light?

The math gets weird and gives an answer of .91 of the speed of light.

When they actually solve the division by 0 equations then all hell will break loose. Kind of like the square root of -1.

Link Posted: 10/11/2004 8:34:56 AM EST
Even better question is what happens when a spaceship doing 99.999% of the speed of light shines it headlights forward? Since light speed is constant does the light not move forward for you to see? Now if you shine said light backwards from a ship going same speed does it almost stand still? Now my brain hurts.h.gif
Link Posted: 10/11/2004 8:38:21 AM EST

Originally Posted By jdovell:
Even better question is what happens when a spaceship doing 99.999% of the speed of light shines it headlights forward? Since light speed is constant does the light not move forward for you to see? Now if you shine said light backwards from a ship going same speed does it almost stand still? Now my brain hurts.



The beam of light will leave the headlight at the speed of light relative to the headlight. Same thing going backwards.

Of course, to someone standing still in space while the ship flies by, the universe will become so warped that John Kerry will suddenly begin telling the truth and W will run around in a pink mumu demanding tax increases on school children.
Link Posted: 10/11/2004 8:42:42 AM EST

Originally Posted By TheCynic:
Relativity.

The fly is not flying in relation to the
ground, but in relation to the car. Same
reason why if you jump in a downward
traveling elevator, you do not leviate.



Try tossing a coin up when seated in Disney's Tower of Terror during it's drop.


Link Posted: 10/11/2004 8:49:35 AM EST

Originally Posted By jdovell:
Even better question is what happens when a spaceship doing 99.999% of the speed of light shines it headlights forward? Since light speed is constant does the light not move forward for you to see? Now if you shine said light backwards from a ship going same speed does it almost stand still? Now my brain hurts.



Waves or photons?
Link Posted: 10/11/2004 8:52:40 AM EST
Link Posted: 10/11/2004 8:55:19 AM EST

Originally Posted By Zaphod:

Originally Posted By jdovell:
Even better question is what happens when a spaceship doing 99.999% of the speed of light shines it headlights forward? Since light speed is constant does the light not move forward for you to see? Now if you shine said light backwards from a ship going same speed does it almost stand still? Now my brain hurts.



The beam of light will leave the headlight at the speed of light relative to the headlight. Same thing going backwards.




I don't think that is correct. If it were so, then the speed of light is variable, and a merely arbitrary measurement. Explain Red/Blue shift if the light from fast objects experiences this.
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