As with any problem like this, it is fairly easy to make a little mistake and not get the exact final answer. For that reason, I encourage you to go through my steps to check for any minor errors.
This is a work problem with integrals. Each horizontal slice is a circle with area = pi*r^2. The radius of the slice depends on the y-coordinate. We can solve for the radius in terms of y using the ratio 4/6 = r/y. So r = 2y/3. Then we integrate from 0 to 5 the integrand: 62.4*pi*(2y/3)^2. The antiderivative is 62.4*pi*4/27*y^3. Plugging in 5 and 0, we get 3630.28 ft-lb. And plugging in 6 and 2, we get 6040.79 ft-lb.
Please let me know if you need any clarification. I'm always happy to answer your questions.
Sep 28th, 2015
Studypool's Notebank makes it easy to buy and sell old notes, study guides, reviews, etc.