24 BULLETIN" 556, U. S. DEPARTMENT OF AGRICULTURE. 
WORK. 
(See p. 15.) 
Work is the product of force and distance, or force acting through 
distance. 
Work is essential in stopping bodies in motion, or in causing motion 
or change of motion of bodies. 1 
Work is measured in inch-pounds, foot-pounds, etc. 
An inch-pound is the work required to raise one pound 1 inch or to 
move a body 1 inch against a resistance of 1 pound. 
FORMULAE USED IN COMPUTING. 
LEGEND. 
A = Area of cross section; square inches. 
B = Area under plate in compression-perpendicular-to-grain tests, 
square inches. 
CS = Crushing strength, pounds per square inch. 
E = Modulus of elasticity, pounds per square inch. 
EL = Fiber stress at elastic limit, pounds per square inch. _ 
J = Greatest calculated longitudinal shear, pounds per square inch. 
K = Constant = 27.7 when weight is in pounds; 0.061 when weight 
is in grams. 
MR = Modulus of rupture, pounds per square inch. 
P = Maximum load, pounds. 
P' =Load at elastic limit, pounds. 
S = Dry specific gravity. 
A = Total deflection or compression at elastic limit, inches, 
b = Width, inches 
d = Distance between centers of collars, inches. 
h = Height, inches. * 
l = Span, inches (in compression parallel to grain 1 = length). 
BENDING. 
Load applied at center: 
0.75XP 
J = 
MR = 
EL = 
E = 
bxh 
1.5xPxl 
bxh 2 
1.5xP'xl 
bxh 2 
P'xl 3 
4 X b X h 3 X A 
