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Mental Block - HSN forum

# Mental Block

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### #1smit

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Posted 04 May 2006 - 10:15 AM

Okay, I cant seem to figure out this question, its as follows:

Two forces acting on an aeroplane in flight are its weight and aerodynamic (lift) force.
The aerodynamic force acts in a direction perpendicular to the wings.
The pilot banks the aeroplane so that it flies at 150m/s in a horizontal circle of radius 4000m.

At what angle must the plane be banked?

### #2Vixus

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Posted 05 May 2006 - 10:05 PM

It's a banked corners question! Now imagine the lift force as the reaction force to the weight (lift = weight).
As it is flying in a constant circle, centripetal force = horizontal component of weight.

Using vector triangles you can figure this out.

Wh = mg sin = mv2/r
sin = v2/rg
= sin-1 (v2/rg)

I got 35. I hope I'm right!

### #3waitingforan_alibi

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Posted 07 May 2006 - 06:52 PM

hi

This question was in my prelim i think (or one similar) and i cant remember the whole thing but the answer turned out to what i scribbled out - it was something like 70 degrees (seemed rediculous).

I ll ask my teacher if i can see the marking scheme and i ll get back (hopefully)

### #4smit

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Posted 09 May 2006 - 09:02 AM

Thanks for the help.

At the time I was making a VERY stupid mistake, that was, central force = v^2/g , no m. And so had an extra m.

I feel so stupid.

cheers.

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