2006-07-04 03:42:32 · 10 answers · asked by Mike 1 in Science & Mathematics ➔ Physics
Wind is not always constant, nor is it always the same on both sides of a flag. Disturbances in the air flow from the flagpole and flag itself cause local variances in the airspeed which in turn cause the flag to flap. In addition, wind often gusts as it moves across surfaces, is heated and cooled by various factors, and is even bent in direction by the rotation of the Earth. A flag on the antenna of a car also does this, for the same reasons.
2006-07-04 03:48:06 · answer #1 · answered by But why is the rum always gone? 6 · 1⤊ 0⤋
The answer is eddies. Eddies are small turbulence - circular motion of the air, caused by the drag, as it flows past the flag. So, the eddies cause the flag cloth to bend and wave. If you keep a flag in a wind tunnel, and blow the air real fast, you would see that the amplitude of the flutter decreases, but the frequency of the flutter increases. You can see the effect, by putting a flag out, as you are driving a car.
At high speeds, the net distorions caused by these turbulence decrease, because the wind flowing past the air is at a much higher speed. The eddies created by drag are quickly broken up the by high speed wind behind it. But, due to the high speed of wind, the number of eddies created (small they may be) per minute goes up. Thus, at high speed, flags flutter faster, but tighter.
2006-07-04 10:57:10 · answer #2 · answered by sebekhoteph 3 · 0⤊ 0⤋
Because the wind isn't constant, the flow varies depending on the objects before the flag, and the material flags are made of, most clothes, aren't naturally stiff, so there's resistance and sensitivity to the wind. Also, another wind could get in the way on one side. To be honest, I doubt your premise that the wind is the same on both sides is even correct.
2006-07-04 10:49:57 · answer #3 · answered by Anonymous · 0⤊ 0⤋
The wind is not the same on both sides. Air is a fluid, and there are small variations even in the small size of the flag. Also, gravity is trying to pull the flag to the ground.
2006-07-04 10:48:11 · answer #4 · answered by Anonymous · 0⤊ 0⤋
There is something known a turbulence. This occurs when the air is not blowing in one specific direction.
However, you have forgotten the flag pole. The latter causes turbulence and the flag waves due to the air flowing past its sides being of unequal.
2006-07-04 10:51:12 · answer #5 · answered by javed 2 · 0⤊ 0⤋
Difference between elastic and non-elastic,..,
the flag is a form of elastic - and since the wind pressure is not uniform on both sides, the pascals definately vary, therefore the flag flutters, occasionally, very rarely when it is really really uniform you do see most of the flag straight, and only a portion fluttering
2006-07-04 10:57:25 · answer #6 · answered by msdniso2004 3 · 0⤊ 0⤋
Wind is "turbulent". This means that it blows in the same general direction but, is full of convections, eddys, vorticies, etc. If it were "laminer" then it would truly all blow in the same direction, (lab conditions only), and the flag, assuming that it was PERFECTLY flat wouldn't wave.
2006-07-04 10:51:48 · answer #7 · answered by Ricky J. 6 · 0⤊ 0⤋
When the wind blows, the wind acts against the cloth of the flag.The cloth, being flexible, bends and flutters with the undulations of the wind which is constantly changing direction.
2006-07-04 10:47:35 · answer #8 · answered by eminem197796 3 · 0⤊ 0⤋
It has to do with different pressures on either side of the flag. Not to mention that drag is created from the pole.
2006-07-04 10:47:13 · answer #9 · answered by Darryl E 2 · 0⤊ 0⤋
Turbulance, and lack of stiffness in the material. Waves form in the cloth, making more turbulance.
Turbulance is non-smooth flow of gas or liquid.
Laminar (layered) is smooth flow.
2006-07-04 10:50:30 · answer #10 · answered by helixburger 6 · 0⤊ 0⤋