quote Originally posted by rogergarrison: 9 or 10 Gs is most that average person can handle.(which is good since a plane can come apart pretty ez) 3 Gs can pull the wings off a Cessna with no problem [This message has been edited by rogergarrison (edited 07-07-2001).]

Most people are going to GLOC below 5-6 G's. That's why the CART drivers at Texas Motor Speedway were having trouble: they were pulling 3 G's vertical and 5.5 lateral. That vectors out to about 6.

Only highly trained pilots with well fitting G suits can approach 10. The USAF is experimenting with laser fitted G suits which have allowed a very few elite pilots to stay conscious for 10 second runs at 12 G's in a centrifuge.

The G load of an ejection is only momentary. EVERYONE GLOC's for a second or so on ejection. That's OK because the 'chute deploys automatically.

[This message has been edited by Will (edited 07-07-2001).]

quote Originally posted by Cliff Pennock: Here's another interesting tid-bit. Black holes do grow in size the more matter they "absorb". It has been calculated that if all matter in the known universe was injected into a black hole, the black hole would grow to the same size as... the known universe. So our universe could actually be a black hole and we wouldn't know it.

I'm sure that's right, but if you put everything in the known universe into a black hole, the only thing that would exist is the black hole meaning that it would be the known universe regardless of it's size.

quote Originally posted by Pontiaddict: I'm sure that's right, but if you put everything in the known universe into a black hole, the only thing that would exist is the black hole meaning that it would be the known universe regardless of it's size.

That is WWWWAAAAYYYYY too deep for 3:00 am.

HOLY COW! so many offical sounding answers from so many credible sources!

and so far they are all wrong!!!

SPEED?!?! IN PHYSICS?! there is no such thing! in physics its call velocity, not speed, the two are NOT interchangable!

and VELOCITY is a VECTOR. So when you are going around in a circle your VELOCITY IS constantly changing - and that is what your acceleration IS! If you average your velocity around a circle it will be ZERO - not a constant, because the directions cancel out!

YIKES! Where do you guys up in canada learn physics from? Watching the bugs bunny/road runner show?!

as for the original question, when you throw a baseball straight up its acceleration changes the instant it leaves your hand, from the force your hand gave to it, to the new total due to gravity (1 G) and the accelration due to friction with the air. So the acceleration going up will be constantly changing, becoming less and less as upward velocity decreases (less and less wind drag).

then on the trip back down acceleration will continue to DECREASE as air resistance increasinly fights the pull of gravity. Eventully, if the ball is thrown high enough, the ball will reach TERMINAL VELOCITY and will fall the rest of the way at a CONSTANT SPEED - therefore, with ZERO acceleration.

These factors cannot be ignored. For example, if you jump off the top of the world trade center (1/4 mile high) or if you jump out of an airplane at 5 miles altitude, you will reach a terminal velocity quickly - the air resistance keeps you from falling any faster. In both cases you will hit the ground at the same speed, about 200 mph, if you are falling flat with your body horizontal. So after about a 1/4 mile of altitude, no matter how far you fall, you hit the ground at the same speed.

Why do people always say, "Ignoring air resistance..." to make things seem easier. Air resistance is the major force in almost all moving objects. You might as well add "ignoring gravity" too.

Why bother to even learn Physics at all if you are going to ignore the MAJOR forces that are in effect, and end up with answers that dont apply to the real world?!?!

when your car is going 140 mph and your foot is on the floor, and your engine is putting out 130HP almost all of that power is being expended fighting AIR RESISTANCE - nothing else.

If you ignore air resistance in calculating how fast a 130HP car can go, then you would be able to gear the car up incredibly high, and acheive speeds of 10s of thousands of miles per hour, until you get to the point where your drive train internal friciton is disapating the entire 130HP of energy.

quote 3 Gs can pull the wings off a Cessna with no problem[/B]

That's more reason to buy a Mooney!

They have been tested by nose diving them and pulling up on the yolk when a maximum speed has been attained.

Thousands of rivets subsequently popped (where at this point most planes are at this stage either consider not airworthy or burning on the ground because their wings couldn't take the stress) and are still considered air worthy by the FAA! That was the 201 J series!

I wonder what would happen if they did that same test with a Mooney 201 J with a 300 Continental Missle engine under the cowel, that has to have speed brakes and extra fuel cells in the wings? Hmmmmm?

Anyways, this from somebody that doesn't fly...

Just call me the PRETENDER!

quote Originally posted by Ken Wittlief: Why do people always say, "Ignoring air resistance..." to make things seem easier. Air resistance is the major force in almost all moving objects. You might as well add "ignoring gravity" too.

Because taking air restance into effect requires fluid dynamics, calculus, and differenential equations. Unless you've taken 300 level aerodynamics classes, you can't figure out air resistance.

quote Originally posted by Steve Normington: Because taking air restance into effect requires fluid dynamics, calculus, and differenential equations. Unless you've taken 300 level aerodynamics classes, you can't figure out air resistance.

F=.5*C_dApv²

Ain't that the formula for air resistance?

quote Originally posted by Ken Wittlief: HOLY COW! so many offical sounding answers from so many credible sources! and so far they are all wrong!!! SPEED?!?! IN PHYSICS?! there is no such thing!

I have been having alot of fun reading this thread and have even sent it to a few other ACTUAL PHYSICISTS just for grins.

Since Ken you were so keen to try to correct others on thier physics knowledge, I will now correct YOU!!!!

There IS such a thing as speed in physics! Any first semester physics course will cover that! Simply put speed is the magnatide of the velocity... Thus the word speedometer! Notice how a speedometer does not tell you your direction, just the magnatude of the velocity vector.

Belittling people and commenting on the stupidity of neglecting such things as air resistance blatently shows your ignorance in the field of physics as any marginally competant physicist realizes that first order approximations are done every day and prove to be extremely useful.

This is the LAST time I will ever look at this thread, so a reply here towards me will be pointless!

Have a yummy sunny day,
Greg Piet - an actual physicist!

quote Originally posted by Steve Normington: That is WWWWAAAAYYYYY too deep for 3:00 am.

That's nothing. If you want deep, consider, that everything ever experienced by anyone that ever existed in the universe could just be a speck of thought from some mold growing in a greater being's fridge. Everyones experiences could just be the daydream of something that only exsted for an instant. It seems real to us, but it could have been one of a million things on that creatures mind.

Funny how the insight of filling a black hole with everything other than itself seems small when you could be a fictional character in a daydream.

Time for sleep. I'll see if thid makes sense when I wake up.

[This message has been edited by Pontiaddict (edited 07-09-2001).]

BIG WORDS!!!! I'M SCARED HOLD ME!!!!

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1984 Sweet Candy Apple red Fiero sport coupe :-D

Oh my gosh - here we go again - I didnt put the little smiley faces on my last post so people would realize I was 'rightously outraged' in a humorour manner

and now people are getting emotionally upset over what happens when you throw a baseball.

the bottom line in physics is you go to college and take 4 or 5 semisters of calc and diff eq, only to learn later in life that they only apply to linear systems, and in real life 99.999% of everything you will encounter is NON linear.

whats more - for NON linear systems there is NO math - there are no equations - things cannot be predicted and they become chaotic and breakdown.

kinda like every subject on this forum after about the third reply.

That is why the weatherman cannot tell you what will happen over your head 4 days from now with more than 40% accuracy.

simple equations of motion only apply in deep space when there are no other bodies of mass around. Get down on the surface of the earth, in the presence of air and water and heat and wind and asphalt and rubber tires, grass lawns and trees, and the first order equations are pretty much useless.

If you dont believe me, try hitting a golf ball without slicing it and then explain to me how X=Xo+VoT+1/2AT^2 accounts for the fact that your golf ball is flying through the air in a cork screw trajectory.

and explain to your opponent that only first order effects count, so even though your ball in now in the woods, you really 'hit' a hole in one.

[come on people -lighten up! this section of the forum is primarilly here for entertainment]

Ken I'm personaly outraged, I think.

quote Originally posted by Cliff Pennock: F=.5*CdApv2 Ain't that the formula for air resistance?

Maybe, I don't know, but if it is, v is constantly changing. Also, what is the coefficient of drag (C_d?) for a baseball?

quote Originally posted by fierobaby: BIG WORDS!!!! I'M SCARED HOLD ME!!!!

The way to a girl's heart is with complex physics equations and metaphysical conundrums.