Cube Projectile Motion: Air Resistance & Cross Sectional Area

[Mike Jones]

We have a solid cube with some mass that we fire as a projectile at some angle. The cube is launched in such a way that two of the faces are perpendicular to the initial velocity vector. Assuming there is air resistance, would the cube change its orientation while it flies, even if the mass is balanced throughout the cube? If not, how can we find the cross sectional area at any given time?

 

[OldEngr63]

If two planes are each perpendicular to a specified vector, they are either the same plane or they are parallel to each other.

I don't think you said what you meant. Would you try again, please?

 

[Danger]

I can't answer your last question; in fact, I doubt that it can be answered. You'd have to have multiple laser scanners tracking the thing constantly.
I will say, just in case your basic goal is weapons development (either real or fictional), that what you've described is one of the worst possible designs for a firearms projectile. Beside its inherent instability, you can't effectively impart the twist that goes into spin-stabilizing a real bullet. Outside of any man-made considerations, remember that air is a dynamic fluid medium, not a constant. A 1 km/hr change in wind speed can throw something off target by a huge amount.

 

[256bits]

While re-arranging your question, and contemplating weapons development, you might want to look at vortex shedding.
http://en.wikipedia.org/wiki/Vortex_shedding

 

[Danger]

That's an excellent link, 256bits, with lots of really nice secondary links.

 

[Mike Jones]

Basically, I'm wondering if it's possible to predict the orientation of a cube as it flies through the air. Based on the responses, it seems as though there are too many variables for such as predictive function to exist without producing inaccurate results.

Thank you for the link though! Very cool.

 

[Danger]

Based on the responses, it seems as though there are too many variables for such as predictive function

I'm guessing that it would be about the same as sending someone into a tornado in a hang-glider and trying to predict where he'll puke.