called weight. Gravity is one type of gravitational force, a force which attracts all
particles and bodies to each other. Gravity acts upon your body during every instant of
(2) Mass. If you were standing on the surface of the Moon, you would weigh
1/6 of your weight on Earth, but your mass would remain the same. Mass is an intrinsic
property of a particle or object that determines its response to a given force. In a given
location, the weight of an object depends upon its mass.
b. Space and Time. Each individual occupies a certain amount of space. We
exist over a span of time. During the passage of time, we change--from an infant, to a
child, to an adult, to an adult of advanced age.
c. Physical States of Matter. The matter around and in us exists in several
states. These various states generally reflect the closeness of the molecules that make
up the matter.
(1) Solid. The most compact organization is the solid, which retains its
specific form and shape.
(2) Liquid. Liquids tend to flow but still stay together.
(3) Gas. Gases also flow but are widely spread and will readily dissipate in
d. Pressure Gradients. Substances that flow (gases and liquids) flow in very
specific directions. They flow from an area of higher pressure or concentration to an
area of lower pressure or concentration as long as the two areas are freely
interconnected. The difference in pressures of two interconnected areas is called a
pressure gradient. When plotted on graph paper, it is in the form of a slope. The
greater the difference, the steeper is the slope and the faster the material flows.
Machines are devices that do work. The different kinds of machines and their
modes of action are the study of applied mechanics. The human body, as already
stated, conforms in its structural organization to the laws of physics. The body uses
several different kinds of machines, such as levers, pulleys, and valves, in its operation.
We refer to these operations as biomechanics.
1-6. LIFE PROCESSES
The planet upon which we live is composed of inanimate (nonliving) materials
such as minerals, water, etc. Living organisms reside upon or in this mass of nonliving
material. You can distinguish living from nonliving material by the fact that living
material carries on a series of functions known as the life processes. A living thing