Question

Find the volume of the solid by rotating the region bounded by y=x^3, y=8, and x=0 about the y axis.

Answer 1

Answer:

Solution : Volume = 96/5π

Step-by-step explanation:

If we slice at an arbitrary height y, we get a circular disk with radius x, where x = y^(1/3). So the area of a cross section through y should be:

A(y) = πx^2 = π(y^(1/3))^2 = πy^(2/3)

And now since the solid lies between y = 0, and y = 8, it's volume should be:

V =  ∫⁸₀  A(y)dy (in other words ∫ A(y)dy on the interval [0 to 8])

=> π ∫⁸₀ y^(2/3)dy

=> π[3/5 * y^(5/3)]⁸₀

=> 3/5π(³√8)⁵

=> 3/5π2^5

=> 96/5π ✓