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Problems in Mathematical Analysis.pdf - pwp.net.ipl.pt

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Sec 7\ Tr<strong>ipl</strong>e Integrals 265<br />

We therefore have<br />

f f f Vx z<br />

-\-y 2<br />

-\-z*dxdydz=\ dcp f dty f r A'COS \|?dr = Ji# 4 .<br />

3. Applications of tr<strong>ipl</strong>e <strong>in</strong>tegrals. The volume of a region of three-dimensional<br />

A'//z-space is<br />

The mass of a solid occupy<strong>in</strong>g the region V is<br />

z) = I <strong>in</strong> the formulas<br />

for the coord<strong>in</strong>ates of the centre of gravity.<br />

The moments of <strong>in</strong>ertia relative to the coord<strong>in</strong>ate axes are<br />

T- J J $ (y* + **) Y (*, U, 2) dx dy dz;<br />

(V)<br />

(V)<br />

=J J J<br />

(V)<br />

(* l<br />

Putt<strong>in</strong>g Y(*0 ^i^ 21 <strong>in</strong> * nese formulas, we get the geometric moments<br />

of <strong>in</strong>ertia of the body.<br />

Al<br />

A. Evaluat<strong>in</strong>g tr<strong>ipl</strong>e <strong>in</strong>tegrals<br />

Set up the limits of <strong>in</strong>tegration <strong>in</strong> the tr<strong>ipl</strong>e <strong>in</strong>tegral<br />

for the <strong>in</strong>dicated regions V.<br />

J J ^f(x,y, z)dxdydz<br />

(V)<br />

'

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