Chapter 13: Problem 1
Explain how to find the balance point for two people on opposite ends of a (massless) plank that rests on a pivot.
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Chapter 13: Problem 1
Explain how to find the balance point for two people on opposite ends of a (massless) plank that rests on a pivot.
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A cake is shaped like a hemisphere of radius 4 with its base on the \(x y\) -plane. A wedge of the cake is removed by making two slices from the center of the cake outward, perpendicular to the \(x y\) -plane and separated by an angle of \(\varphi\) a. Use a double integral to find the volume of the slice for \(\varphi=\pi / 4 .\) Use geometry to check your answer. b. Now suppose the cake is sliced by a plane perpendicular to the \(x y\) -plane at \(x=a > 0 .\) Let \(D\) be the smaller of the two pieces produced. For what value of \(a\) is the volume of \(D\) equal to the volume in part (a)?
Consider the following two-and three-dimensional regions. Specify the surfaces and curves that bound the region, choose a convenient coordinate system, and compute the center of mass assuming constant density. All parameters are positive real numbers. A solid cone has a base with a radius of \(a\) and a height of \(h\). How far from the base is the center of mass?
In polar coordinates an equation of an ellipse with eccentricity \(0 < e < 1\) and semimajor axis \(a\) is \(r=\frac{a\left(1-e^{2}\right)}{1+e \cos \theta}\) a. Write the integral that gives the area of the ellipse. b. Show that the area of an ellipse is \(\pi a b,\) where \(b^{2}=a^{2}\left(1-e^{2}\right)\)
Miscellaneous volumes Choose the best coordinate system for finding the volume of the following solids. Surfaces are specified using the coordinates that give the simplest description, but the simplest integration may be with respect to different variables. Volume of a drilled hemisphere Find the volume of material remaining in a hemisphere of radius 2 after a cylindrical hole of radius 1 is drilled through the center of the hemisphere perpendicular to its base.
Use polar coordinates to find the centroid of the following constant-density plane regions. The region bounded by one leaf of the rose \(r=\sin 2 \theta,\) for \(0 \leq \theta \leq \pi / 2\) \((\bar{x}, \bar{y})=\left(\frac{128}{105 \pi}, \frac{128}{105 \pi}\right)$$(\bar{x}, \bar{y})=\left(\frac{17}{18}, 0\right)\)
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