Engineering Fundamentals: An Introduction to Engineering, 4th ed.c

8.6 Angular Motion 221

8.6 Angular Motion

In the next two sections, we will discuss angular motion, including angular speeds and accel-

erations of rotating objects.

Angular (Rotational) Speeds

In the previous section, we explained the concept of linear speed and acceleration. Now we will con-

sider variables that define angular motion. Rotational motion is also quite common in engineering

applications. Examples of engineering components with rotational motion include shafts, wheels,

gears, drills, pulleys, fan or pump impellers, helicopter blades, hard drives, CD drives, and so on.

The average angular speed of a line segment located on a rotating object such as a shaft is

defined as the change in its angular position (angular displacement) over the time that it took

the line to go through the angular displacement.

v (8.13)

¢u

¢t

line segment



A stroboscope and

a tachometer.

Source:© Roger Ressmeyer/ CORBIS Source:© Alan Schein Photography/

CORBIS / Magma

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