Chapter 6: Problem 8
Let \(R\) be the region bounded by the following curves. Use the shell method to find the volume of the solid generated when \(R\) is revolved about the \(y\) -axis. $$y=6-x, y=0, x=2, \text { and } x=4$$
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Chapter 6: Problem 8
Let \(R\) be the region bounded by the following curves. Use the shell method to find the volume of the solid generated when \(R\) is revolved about the \(y\) -axis. $$y=6-x, y=0, x=2, \text { and } x=4$$
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A power line is attached at the same height to two utility poles that are separated by a distance of \(100 \mathrm{ft}\); the power line follows the curve \(f(x)=a \cosh (x / a) .\) Use the following steps to find the value of \(a\) that produces a sag of \(10 \mathrm{ft}\) midway between the poles. Use a coordinate system that places the poles at \(x=\pm 50\). a. Show that \(a\) satisfies the equation \(\cosh (50 / a)-1=10 / a\) b. Let \(t=10 / a,\) confirm that the equation in part (a) reduces to \(\cosh 5 t-1=t,\) and solve for \(t\) using a graphing utility. Report your answer accurate to two decimal places. c. Use your answer in part (b) to find \(a,\) and then compute the length of the power line.
Evaluate the following integrals. $$\int_{0}^{1} \frac{16^{x}}{4^{2 x}} d x$$
a. Confirm that the linear approximation to \(f(x)=\tanh x\) at \(a=0\) is \(L(x)=x\) b. Recall that the velocity of a surface wave on the ocean is \(v=\sqrt{\frac{g \lambda}{2 \pi} \tanh \left(\frac{2 \pi d}{\lambda}\right)} .\) In fluid dynamics, shallow water refers to water where the depth-to-wavelength ratio \(d / \lambda<0.05 .\) Use your answer to part (a) to explain why the shallow water velocity equation is \(v=\sqrt{g d}\) c. Use the shallow-water velocity equation to explain why waves tend to slow down as they approach the shore.
Behavior at the origin Using calculus and accurate sketches, explain how the graphs of \(f(x)=x^{p} \ln x\) differ as \(x \rightarrow 0\) for \(p=\frac{1}{2}, 1,\) and 2
A cylindrical water tank has height 8 m and radius \(2 \mathrm{m}\) (see figure). a. If the tank is full of water, how much work is required to pump the water to the level of the top of the tank and out of the tank? b. Is it true that it takes half as much work to pump the water out of the tank when it is half full as when it is full? Explain.
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