APPLIED MECHANICS 
CHAPTER I 
PRELIMINARY 
(Mainly for Reference) 
1. Definitions Relating to Divisions of Subject.—Newton used the 
term mechanics for “the science of machines and the art of making 
them,” but the term has been used by most writers since Newton’s time 
for the science which treats of the laws of motion and force. This 
includes (1) kinematics, the science of motion without reference to its 
cause ; i) statics, the science of forces which balance one another ; and 
(3) kinetics, the science of unbalanced forces, or the relations between 
motion and force. Many modern writers use the term dynamics in the 
same sense as that of mechanics as just defined, but the most logical 
writers restrict the term dynamics to statics and kinetics, and consider 
kinematics as a branch of pure mathematics. Writers who use the term 
mechanics in place of dynamics generally apply the latter term to what 
has been defined above as kinetics. 
In statics the forces considered may act at a point, or on a solid, a 
liquid, or a gas. That branch of statics which considers the relations 
between forces acting on a liquid at rest is called hydrostatics, and that 
branch which considers the equilibrium of a gas is called pneumatics. In 
hydrodynamics the relations between motion and force in fluids is con- 
sidered. Hydraulics relates to the application of the principles of hydro- 
statics and hydrodynamics to engineering. 
2. Values of Various Constants.—Except where otherwise given, 
the values of the more common constants required in working the 
exercises in this book should be taken as given below. Various useful 
functions of 7 are also given. 
Ratio of the circumference of a circle to its diameter = 7 = 3°1416. 
72=9-8696. 7*=31-0063, Yr=1:7725. fr =1°4646, 
© 1 =Q: te ° 1 =() 9 1 ='68? 
Zr O13 7,=003225, 7 =05642, 7, = 06828. 
1=0:3183, Log + =0°49715. 
Accelerating effect of gravity =g = 32-2 feet per second per second. 
Weight of 1 cubic foot of water = 62°3 Ibs. 
1 gallon of water at 62° F. weighs 10 lbs, 
A 
