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Basics of Fluid Mechanics, 2014a

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CHAPTER 3<br />

Review <strong>of</strong> <strong>Mechanics</strong><br />

This author would like to express his gratitude to Dan<br />

Olsen (former Minneapolis city Engineer) and his friend<br />

Richard Hackbarth.<br />

This chapter provides a review <strong>of</strong> important definitions and concepts from <strong>Mechanics</strong><br />

(statics and dynamics). These concepts and definitions will be used in this book<br />

and a review is needed.<br />

3.1 Kinematics <strong>of</strong> <strong>of</strong> Point Body<br />

A point body is location at time, t in a location, R. ⃗ The velocity is derivative <strong>of</strong><br />

the change <strong>of</strong> the location and using the chain role (for the direction and one for the<br />

magnitude) results,<br />

change in R<br />

direction change in perpendicular<br />

to R<br />

{ }} {<br />

+ ⃗ω × R<br />

{ }} {<br />

⃗U = d⃗ R<br />

dt = dR<br />

⃗ dt ∣ ⃗ (3.1)<br />

R<br />

Notice that ⃗ω can have three dimensional components. It also can be noticed that this<br />

derivative is present derivation <strong>of</strong> any victory. The acceleration is the derivative <strong>of</strong> the<br />

velocity<br />

Coriolis<br />

“regular<br />

angular<br />

acceleration”<br />

centrifugal<br />

{ }} { acceleration<br />

acceleration<br />

⃗a = d⃗ U<br />

dt = d 2⃗ ∣ { }} { acceleration {<br />

R ∣∣∣∣R (<br />

dt 2 + ⃗R × d⃗ω ) { }} { ( }} {<br />

( )<br />

+ ⃗ω × ⃗R d × ⃗ω + 2<br />

⃗ )<br />

R<br />

× ω<br />

dt<br />

dt ∣<br />

R<br />

(3.2)<br />

Example 3.1:<br />

A water jet is supposed be used to extinguish the fire in a building as depicted in Figure<br />

53

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