Sylvan

Arthur P,
I had asked you why you used pound seconds as opposed to slug ft/sec for momentum and I finally realized that it was a dumb question. If I'd thought about it a bit I would have known.

Following just the units through...
Momentum = mass x velocity = slugs x ft/sec
slugs = pounds/ft/sec/sec

so momentum = pounds/ft/sec/sec x ft/sec = pounds x sec or we say just pound seconds

so slug ft/sec is identical to pound seconds

KE is talked about in foot pounds for the same reason. Its just the result of following the units through to the simplest terms. I guess sometimes we get so used to saying something we forget why. I did anyway.