Section 4.9

Computation of Moments. Coordinates of the Centroid

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Problem 2501

Find the static moment and moment of inertia of a semicircular arc of radius aa with respect to the diameter through its two endpoints.

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Problem 2501.1
[NO TASK]
Problem 2502

Find the static moment and moment of inertia of a uniform triangular plate with base bb and height hh with respect to its base (ρ=1\rho =1).

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Problem 2502.1
[NO TASK]
Problem 2503

Find the moment of inertia of a uniform elliptical plate with semi-axes aa and bb with respect to its major axis (ρ=1\rho =1).

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Problem 2504

Find the static moment and moment of inertia of a uniform cone with base radius rr and height hh with respect to its base plane (ρ=1\rho =1).

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Problem 2504.1
[NO TASK]
Problem 2505

Prove Pappus's first theorem: the area of the surface of revolution generated by rotating an arc CC about an axis that does not intersect it equals the product of the length of the arc and the length of the circle traced out by the centroid of the arc.

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Problem 2506

Prove Pappus's second theorem: for a solid of revolution generated by rotating an area SS about an axis that does not intersect it, its volume equals the product of the area SS and the length of the circle traced out by the centroid of that area.

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Problem 2507

Find the coordinates of the centroid of the circular arc: x=acos⁡φx=a\cos \varphi, y=asin⁡φy=a\sin \varphi (∣φ∣⩽α⩽π\left|\varphi \right|\leqslant \alpha \leqslant \pi).

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Problem 2508

Find the coordinates of the centroid of the area enclosed by the parabolas: ax=y2ax=y^{2}, ay=x2ay=x^{2} (a>0a>0).

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Problem 2509

Find the coordinates of the centroid of the area

x2a2+y2b2⩽1(0⩽x⩽a,0⩽y⩽b) \dfrac {x^{2}}{a^{2}}+\dfrac {y^{2}}{b^{2}}\leqslant 1\quad (0\leqslant x\leqslant a,0\leqslant y\leqslant b)
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Problem 2510

Find the coordinates of the centroid of a uniform hemisphere of radius aa.

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Problem 2511

Find the coordinates of the centroid C(φ0,r0)C(\varphi_{0},r_{0}) of the arc OPOP from the point O(−∞,0)O(-\infty ,0) to the point P(φ,r)P(\varphi ,r) on the logarithmic spiral

r=aemφ(m>0) r=ae^{m\varphi }\quad (m>0)

As the point PP moves, what curve does the point CC trace out?

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Problem 2512

Find the coordinates of the centroid of the area enclosed by the curve r=a(1+cos⁡φ)r=a(1+\cos \varphi ).

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Problem 2513

Find the coordinates of the centroid of the area enclosed by the first arch of the cycloid x=a(t−sin⁡t)x=a(t-\sin t), y=a(1−cos⁡t)y=a(1-\cos t) (0⩽t⩽2π0\leqslant t\leqslant 2\pi) and the OxOx axis.

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Problem 2514

Find the coordinates of the centroid of the solid of revolution obtained by rotating the area 0⩽x⩽a0\leqslant x\leqslant a, y2⩽2pxy^{2}\leqslant 2px about the OxOx axis.

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Problem 2515

Find the coordinates of the centroid of the hemisphere x2+y2+z2=a2x^{2}+y^{2}+z^{2}=a^{2} (z⩾0z\geqslant 0).

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