Will it take off?

[JohnA]

Now, uncouple the hose from the

spigot and connect the hose to a pump. Submerge the sprinkler in some

water, so now when you turn on the pump the sprinkler is drawing water

in through the pipes. What happens to the sprinkler? How does it

move, if at all?

The sprinkler will spin in the opposite direction IF the

velocity of the water pulled into the arms generates enough reaction

force to overcome the friction of the water against the outside of the

arms.

[klipschaholik]

Sputnik, you handle this one.

[Travis In Austin]

Shouldn't it be 1.146 degrees and 6.71 degrees?

10/500 arcTan = 1.146

10/85 arcTan = 6.71

Incorrect, but I am amazed that you are so good with Trig. I could never understand it.

Travis

[Travis In Austin]

dwilawyer,

OK, I'll bite - I just wanted to make sure it wasn't some sort of lawyer trick. In one hour, both planes should be 10 miles north of the intended flight path. The Gulf Stream will have travelled 500 miles east and 10 miles north and will be off course by ATAN(10/500) or 1.46 degrees. The Piper will have travelled 85 miles east and will also be 10 miles north of the intended flight path and will be off course by ATAN(10/85) or 6.71 degrees.

D-MAN will still be stuck on the conveyor.

Correct,

Both will be 10 miles off course

So here is another, plane takes off with no wind travels for a while at 100 mph, with a ground speed of 100 mph, then hits a front with a direct headwind of 100 mph. As it flys into the head wind what is its airspeed, and what is its ground speed, after awhile of not making any headway he does a 180 (heads back the opposite direction), what happens to the airplane, if anything, other then normal flight, and if it is in normal flight, what is its airspeed and its ground speed?

Travis

[sputnik]

Now, uncouple the hose from the

spigot and connect the hose to a pump. Submerge the sprinkler in some

water, so now when you turn on the pump the sprinkler is drawing water

in through the pipes. What happens to the sprinkler? How does it

move, if at all?

The sprinkler will spin in the opposite direction IF the

velocity of the water pulled into the arms generates enough reaction

force to overcome the friction of the water against the outside of the

arms.

This one was Ray's fault - the famous Feynman sprinkler.

The sprinkler should not turn at all. You can do some fast talking, skewing some physics, and convince people the sprinkler can turn either way. In the normal case, where water jets out of the sprinkler nozzle, it's pretty easy to predict the reaction intuitively. In the submerged suction case, the water isn't jetting into the nozzle but is flowing toward the nozzle uniformly from all angles. The forces all cancel and there is no net force to turn the sprinkler. You can't pull on a mass of water like a string.

[Travis In Austin]

Airflow over the wings is what makes it fly, and with zero air speed over the wings, zero flight.

DM

Why do you assume there is "zero air speed"? What force is exerted by the conveyor on the plane to impede the plane's forward motion?

I have to go out for a while. So you have time to think.

Are you NUTS?! the jet engines exhausting one way and the conveyor going the opposite direction at exactly the same compensating speed? Try ZERO air speed...

To think otherwise is shockingly stupid, but I see you've already signed up for that one.

I'm going out for awhile so you have time to not be as ...

DM

DM,

As the biggest former proponent of "won't fly" I understand where you are coming from. but it will develop ground speed, thus having air moving over its wings. Think of it is ice, if you were in a car if you pressed the accelerator the wheels would just spin and spin, but with a plane you easly move forward. A plane, assuming tires with zero or no friction would just sit on the belt/moving runway in fixed position even if the belt is moving 100 mph in reverse. It is sort of a trick question, the wording makes you assume that the plane would remain stationairy because the belt is moving in reverse. However, with an airplane, brakes off, they are free spinning so the belt can move in reverse at 5 mph or 500 mph, they are just going to make the wheels spin, the plane can still go forward because the prop/jet will move the plane ahead independant of the wheels spinning in reverse. The wheels are free spining. As soon as you apply power to the airplanes engine it would roll forward because there is nothing to hold the airplane back. The way I originally read the question I thought that the plane would remain in one place, and I agree with you, it would not fly if it did so. But it won't remain in one place, it will move forward, it will gather ground speed, it will have air moving air over its wings, it will get up to stall speed, it will rotate, and it will take off, over just as long a distance as if it was sitting on concrete.

Travis

[sputnik]

Shouldn't it be 1.146 degrees and 6.71 degrees?

10/500 arcTan = 1.146

10/85 arcTan = 6.71

Incorrect, but I am amazed that you are so good with Trig. I could never understand it.

Travis

Wait a minute. When they've both travelled the same distance (west to east), won't the Piper be further away from the intended destination. Wouldn't it (the Piper) be considered to be further off course?

[Travis In Austin]

But I digress, none of this stuff matters compared to the question: If a tree falls in the middle of the forest, and no one is around to hear it, does it make a noise. And if it does make a noise, does it sound better live, or recorded and played back through Klipsch, Bose or B&W speakers. If it sounds better through Klipsch speakers, which model? If one model is better then another, which finish. Does it matter if the tree is pine or oak, does it matter if the Klipsch speaker is make out of pine plywood or oak?

Does it matter if the tree almost hits a bear taking his morning constitutional?

Or do all of these questions beg the question: Is there eternal life?

Travis

[Clarence]

smart people are funny.

[klipschaholik]

So Travis, are you looking for the forum to file your flight plan for you too? LOL. Do we have to show our work and do we get a grade?

If he flies directly into a head wind equal to his ground speed he would slow to a ground speed of zero. After turning around with a tailwind of 100mph his ground speed would increase to 200mph and his air speed would still be 100mph, ideal conditions. That's why airlines like to fly with the jet stream; get's you there on time and saves fuel.

[Travis In Austin]

smart people are funny.

Well I know you are not talking about me, because I know I am not smart. It must be Sputnik doing his long hand trig equations and astro-physics.

Travis

[Travis In Austin]

double post

[Ray Garrison]

Now, uncouple the hose from the

spigot and connect the hose to a pump. Submerge the sprinkler in some

water, so now when you turn on the pump the sprinkler is drawing water

in through the pipes. What happens to the sprinkler? How does it

move, if at all?

The sprinkler will spin in the opposite direction IF the

velocity of the water pulled into the arms generates enough reaction

force to overcome the friction of the water against the outside of the

arms.

This one was Ray's fault - the famous Feynman sprinkler.

The sprinkler should not turn at all. You can do some fast talking, skewing some physics, and convince people the sprinkler can turn either way. In the normal case, where water jets out of the sprinkler nozzle, it's pretty easy to predict the reaction intuitively. In the submerged suction case, the water isn't jetting into the nozzle but is flowing toward the nozzle uniformly from all angles. The forces all cancel and there is no net force to turn the sprinkler. You can't pull on a mass of water like a string.

Well, maybe...

Look at it this way. Think simple conservation of momentum. When we start, the water is a mass at rest. After we finish sucking it in through the sprinkler and blowing it out the pump, I'm not sure what, exactly, it's doing, but it's certainly not at rest. Force has been imparted to the water to accelerate it, and move it in some direction. What happens from a Neuton's 3rd law perspective here? Please note I have no effing idea what the answer is, and judging from Google neither do Cal Tech, MIT, RPI, or a whole gaggle of really smart people who like to chatter on about things like this.

BTW of course it takes off. I *STILL* like my roller coaster example.

[oldtimer]

But I digress, none of this stuff matters compared to the question: If a tree falls in the middle of the forest, and no one is around to hear it, does it make a noise. And if it does make a noise, does it sound better live, or recorded and played back through Klipsch, Bose or B&W speakers. If it sounds better through Klipsch speakers, which model? If one model is better then another, which finish. Does it matter if the tree is pine or oak, does it matter if the Klipsch speaker is make out of pine plywood or oak?

Does it matter if the tree almost hits a bear taking his morning constitutional?

Or do all of these questions beg the question: Is there eternal life?

Travis

Of course it makes a noise. The bear and others would hear it, the insects would feel it. Equally obvious is that live sounds best. It matters if it is pine or oak to the organisms that feast on dead wood, some prefer one or the other. It matters to the bear if he almost gets hit because its better than being hit. Furthermore: yes there is eternal life but that does not mean you will have it.

[klipschaholik]

I agree Sputnik as the slower plane will be forced further away due to the crosswind vector which will require a greater correction (right rudder) to get back on the intended course

[Travis In Austin]

But I digress, none of this stuff matters compared to the question: If a tree falls in the middle of the forest, and no one is around to hear it, does it make a noise. And if it does make a noise, does it sound better live, or recorded and played back through Klipsch, Bose or B&W speakers. If it sounds better through Klipsch speakers, which model? If one model is better then another, which finish. Does it matter if the tree is pine or oak, does it matter if the Klipsch speaker is make out of pine plywood or oak?

Does it matter if the tree almost hits a bear taking his morning constitutional?

Or do all of these questions beg the question: Is there eternal life?

Travis

Of course it makes a noise. The bear and others would hear it, the insects would feel it. Equally obvious is that live sounds best. It matters if it is pine or oak to the organisms that feast on dead wood, some prefer one or the other. It matters to the bear if he almost gets hit because its better than being hit. Furthermore: yes there is eternal life but that does not mean you will have it.

Which brand of speakers? Which finish. Since there is eternal life, is that achieved with good works or faith?

[klipschaholik]

Think of it this way; if you stick a garden hose in your swimming pool and turn on the water the hose wiggles back and forth from the forces of the water being expelled. If you stick the hose into the water and attach the other end to a pump the hose in the pool will just sit on the bottom and suck in the water as there is no force being exerted on the hose to cause movement. That's what I think; Add $.50 more to that and you can buy a cup of coffee at the Waffle House.

[Travis In Austin]

Equally obvious is that live sounds best.

Is that true? Does Pink Floyd's Dark Side of the Moon sound better in it near perfect studio mix, or in concert. If given the choice of hearing DSOM, would you prefer to listen to it on a system you were allowed to create without regard to cost, or live but you had to wear a blindfold during the entire concert?

Of course that reminds me of another very important question. Which one is Pink?

[oldtimer]

Equally obvious is that live sounds best.

Is that true? Does Pink Floyd's Dark Side of the Moon sound better in it near perfect studio mix, or in concert. If given the choice of hearing DSOM, would you prefer to listen to it on a system you were allowed to create without regard to cost, or live but you had to wear a blindfold during the entire concert?

Of course that reminds me of another very important question. Which one is Pink?

Live is best regarding a tree falling in the woods. I was not answering a question about DSOM.

[oldtimer]

The question of speakers was ignored because the tree sounds best live. As for eternal life, works or faith has nothing to do with it, since just because there is eternal life, it doesn't mean that you will have it.