Q. Let R be the region bounded by the curves y=x2, x=0, and y=6. What is the volume of the solid generated by rotating R about the y-axis?
Identify Volume Calculation Method: To find the volume of the solid generated by rotating the region R about the y-axis, we can use the disk method. The volume V of the solid is given by the integral from y=0 to y=6 of the area of the disk at each y-value. The radius of each disk is the x-value on the curve y=x2, which is x=y. The area of each disk is π times the square of the radius.
Set Up Integral: Set up the integral for the volume V using the disk method. The integral will be from y=0 to y=6 of π(y)2dy.
Simplify Integrand: Simplify the integrand. Since (y)2 is just y, the integral becomes ∫06πydy.
Evaluate Integral: Evaluate the integral. The antiderivative of πy with respect to y is (π/2)y2. We need to evaluate this from y=0 to y=6.
Plug in Limits: Plug in the limits of integration. The volume V is [(2π)62]−[(2π)02].
Calculate Volume: Calculate the volume. V=(π/2)×36−0=18π.
More problems from Find values of derivatives using limits