UNITS AND DEFINITIONS RELATED TO BIOMECHANICAL AND ELECTROMYOGRAPHICAL MEASUREMENTS - Biomechanics and Motor Control of Human Movement - page 363

TABLE B.2 (Continued)

Name of

Physical Quantity Symbol SI Unit Definition

m 2

Mass moment of
inertia

I kg · Measure of a body's resistance to

accelerated angular motion about
a given axis; equal to the sum of
the products of the masses of its
differential elements and the
squares of their individual
distances from that axis.

s − 1 Linear momentum p kg · m · Vector quantity possessed by a

moving rigid body, quantified by
the product of its mass and the
velocity of its mass center.

m 2 s − 1 Angular momentum L kg · · Vector of the linear momentum of

a rigid body about a point; the
product of the linear momentum
and the perpendicular distance
of the linear momentum from
the point. For planar movement,
the angular momentum is the
product of the moment of inertia
in the plane about its centroid
and the angular velocity in the
plane.

Moment of force M N · m Turning effect of a force about a

point; the product of the force
and the perpendicular distance
from its line of action to that
point.

Pressure, normal
stress, shear stress

p pascal (Pa) Intensity of a force applied to, or

distributed over, a surface; the
force per unit area. 1 Pa is the
pressure resulting from 1 N
applied uniformly and in a
directional perpendicular over an
area of 1 m 2 .(1Pa

= 1N ·

m − 2 .)

Linear strain
Shear strain

ε
γ

Deformation resulting from stress
measured by the percentage
change in length of a line (linear
strain) or the change in angle of
an initially perpendicular line
(shear strain).

(continued)