What does KT really mean??

[Kimball]

quote:

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Originally posted by rdouglass:
The gravity changes as you move further from the "center" of the planet (or body). I know some of you are going to get me 'cause this doesn't keep its accuracy once you get below the surface - the gravity changes based on a complex mathematical formula.

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The formula to which you refer is

F=G*M1*M2/R^2

G = Universal Graviation Constant (6.67E-11 m^3/(s^2*kg, or 3.32E-11 lbf*ft^2/lbm^2)
M1 = mass of object 1 (kg or lbm)
M2 = mass of object 2 (kg or lbm)
R = distance between the center of mass of each(m or ft)

I beleive this formula holds true even below the surface of the earth since is measures the distance between the centers of mass. In the english engineering system of units, mass is measured in lbm in lieu of slugs. Therefore 1 lbm is numerically equal to 1 lbf. There are 32.174 lbm in one slug. There is also a funny conVersion factor, gc = 32.174 (ft-lbm)/(lbf-s^2).

This is why 1 lbm is equal to 1 lbf. F=ma, from Newton's second law of motion. In the English Engineering system, we introduce that funny little gc into the equation, F=ma/gc (a=the acceleration of gravity, 32.174 ft/s^2 on earth at sea level)

so

1 lbf = (1 lbm)*(32.174 ft/s^2)/(32.174 ft-lbm/lbf-s^2)

1 = 1

We engineers is weird.