Chapter 5: Q30P (page 257)

In Problems 17 to 30, for the curve $y = \sqrt{x}$ , between $x = 0$ and $x = 2$ , find:
The moment of inertia about y the axis of the solid of revolution if the density is $| x y z |$ .

Short Answer

Expert verified

The moment of inertia about the -axis of the solid is, $I = \frac{32}{5}$ .

Step by step solution

Definition of Density Function

For obtaining the probabilities associated with the random variable which is continuous in nature, the integral of the density function is determined.

Representation of the area bounded by the curve

Draw the bounded region for the curve.

Calculation of the moment of inertia

As the density function is symmetric in x, y and z integrate over the first octant and then multiply the result by 4.

Determine the moment of inertia about the y-axis of the solid.

$l = 4 \int_{0}^{2} x d x \int_{0}^{\sqrt{x}} y d y \int_{0}^{\sqrt{x - y^{2}}} z d z (x^{2} + z^{2}) = 4 \int_{0}^{2} x d x \int_{0}^{\sqrt{x}} y d y {(\frac{1}{2} x^{2} z^{2} + \frac{1}{4} z^{4})}_{0}^{\sqrt{x - y^{2}}} = 4 \int_{0}^{2} x d x \int_{0}^{\sqrt{x}} y d y (\frac{1}{2} x^{2} (x - y^{2}) + \frac{1}{4} {(x - y^{2})}^{2}) = 4 \int_{0}^{2} x d x \int_{0}^{\sqrt{x}} y d y (\frac{1}{2} x^{3} - \frac{1}{2} x^{2} y^{2} + \frac{1}{4} x^{2} - \frac{1}{4} y^{4})$

Integrate over .

$l = 4 \int_{0}^{2} x d x {(\frac{1}{4} x^{3} y^{2} - \frac{1}{8} x^{2} y^{4} + \frac{1}{8} x^{2} y^{2} - \frac{1}{8} x y^{4} + \frac{1}{24} y^{6})}_{0}^{\sqrt{x}} = 4 \int_{0}^{2} x d x (\frac{1}{8} x^{4} + \frac{1}{24} x^{3}) = [\frac{1}{12} x^{6} + \frac{1}{30} x^{3}] = \frac{32}{5}$

Thus, the moment of inertia about the -axis of the solid is, $l = \frac{32}{5}$ .

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In Problems 17 to 30, for the curve $y = \sqrt{x}$ , between $x = 0$ and $x = 2$ , find:
The moment of inertia about y the axis of the solid of revolution if the density is $| x y z |$ .

Short Answer

Step by step solution

Definition of Density Function

Representation of the area bounded by the curve

Calculation of the moment of inertia

One App. One Place for Learning.

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In Problems 17 to 30, for the curve y=x, between x=0and x=2, find:The moment of inertia about y the axis of the solid of revolution if the density is |xyz|.

Short Answer

Step by step solution

Definition of Density Function

Representation of the area bounded by the curve

Calculation of the moment of inertia

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Physics Textbooks

Translational Dynamics

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In Problems 17 to 30, for the curve $y = \sqrt{x}$ , between $x = 0$ and $x = 2$ , find:
The moment of inertia about y the axis of the solid of revolution if the density is $| x y z |$ .