Question about G-forces

[ufmc]

Well this is my last shot at this friggin test and I've been one point shy each time. I am terrible at standardized tests and am pretty confident I'll pass this time. I've been remembering questions from the test that I had a hard time w/ and found answers but one is sticking out in my head like crazy. Theres an illustration of a plane w/ a pilot in the cockpit and there are three positions the airplane is in. The plane is completely inverted w/ the wheels straight in the air, the plane is climbing strait up w/ the pilot in a horizontal position looking straight up, and the plane is descending nose straight down w/ the pilot again horizontal looking directly at the ground. In which of these positions is the pilot feeling the most G's???

Any help would be awesome!

 

[Fly Navy]

Top of the loop. For the pilot to feel 1 G at the top of the loop, he must actually be pulling 2 Gs to counter the 1 G of gravity. However, it feels no different to him.

 

[Brett327]

I can't wait to hear the answer!

Brett

 

[UMichfly]

I think it's when the plane is climbing straight up. This problem is just a variation of those god-awful elevator problems in physics 1. The acceleration will be the sum of the gravity and the upwards acceleration. In the horizontal case, the accelleration will be just that of gravity and in the diving case, the net acceleration will be gravity minus the downward acceleration of the plane.

 

[mules83]

I agree with umichfly. With the plane inverted as you say in the picture, the pilot is just hanging there.....with no postive G's. (?)

 

[Kolja]

um - all I know is in an F-16 doing 5 bills at the numbers, you'll hit 8 Gs TWICE in the break. I was only expecting the one. The second one hurt.

 

[gregsivers]

If its flying upside down, yes just hanging there with negative Gs. But if its in a loop I think Fly is right, cause you're pulling Gs that keep you in the seat. But then we're not really able to do vertical in the T-34, so not sure about that one.

 

[Fly Navy]

Guys, you're WAY over-analyzing this problem. It's academic. Unless you state otherwise ufmc, we should assume it is a 1G loop. Realistic? No. But it's a very academic and very classic physics problem. Now, it's been forever since I've even looked at that, but I still stand by the top of the loop. We've all seen something like this at one point in school. Stop monkey-fvcking it into something it isn't.

 

[gregsivers]

I'm gonna quit reading the replies here, I'm getting confused. :icon_tong

 

[Fly Navy]

Actually, at the top of the loop, the pilot would need to "pull" zero g's. God's g is pulling him down at 1 g. If he pulled 2 g's at this point (imagine the g's going straight out the top of his head, lift vector placement for the advanced), there would be a 3 g acceleration of the aircraft. Conversely, at the bottom of the loop, the pilot needs to pull 2 g's to oversome the downward acting 1 g of God to achieve a net upward acceleration of 1 g on both himself and the aircraft. Not overthinking this one, just breaking it down stick monkey style.

Stick monkey is not what they're asking, if I remember the question correctly (aka years ago). They don't expect you to know that.

The classic physics loop question has the pilot experiencing 1 G continuously. When the aircraft is inverted, the reference for the aircraft is also inverted, but to the pilot it is the same... 1 G is his a$$ in the seat. In order to feel 1 G in the seat, he must have 2 Gs pulling him into the seat in order to counteract the 1 G that gravity already has. Centripital force. He's constantly changing his tangental velocity. What's the old equation?

Vt/R = Ac...... there is a square in there somewhere if I remember.....

See what I'm saying? You and I are attacking this from different perspectives. Go all the way back to basic vector physics to hit this problem.... that's what I did.... Then again, it'd be better if the author of the thread could clarify his problem somewhat.... cause either you or I could be correct, depending on the wording of the question.

 

[Fly Navy]

Reading the wording of the question again, the pilot feeling most G's, maybe it's not the classic 1 G problem. If that's the case, then I'm in agreement with you, it's the bottom of hte loop. Your basic 4 G pullup.... it's high at the bottom, and obviously you're not 4 G over the top.

 

[Fly Navy]

I'm gonna quit reading the replies here, I'm getting confused. :icon_tong

You had to pass physics to be a Naval Officer. Engage your brain!

 

[gregsivers]

Oh Physics and I didn't get along too well. Pass I did, with a D. Not good memories from physics.

 

[Jedj]

Is this the most painful disscussion ever, or is it just me. personally, UFMC, I think its a BS question that they are asking.

Besides, I was a poly sci major, what the hell do I know about anything. (IE, dont feel bad about missing that question, I'm sure I, and a lot of others, would've too)

 

[Fly Navy]

I see where we were attacking from different angles now. I wasn't looking at a 1g problem at all. "Pulling" vs. "feeling", I guess that's the question here.

Egg shaped loop anyone?

You're a geek, UI. I love it. Unite!

I think you're the right one in this question.