Physics 211, Homework Set #9

These problems are due Friday, May 14, at 5 PM. You may place your solutions in the mailbox outside my office door, or bring them into class.

The grading scheme for the homework set is as follows: three of the problems will be chosen to count for 10 points, and you may be given partial credit on them. You will receive 1 point for at least attempting each of the other questions. However, you do not know which of the questions will be chosen for detailed grading ... and therefore you should do them all.

1. Cutnell and Johnson, Chap 9, problem 2
2. Cutnell and Johnson, Chap 9, problem 3
3. Cutnell and Johnson, Chap 9, problem 12
4. Cutnell and Johnson, Chap 9, problem 17
5. Cutnell and Johnson, Chap 9, problem 24
6. Cutnell and Johnson, Chap 9, problem 29
7. Cutnell and Johnson, Chap 9, problem 34
8. Cutnell and Johnson, Chap 9, problem 45
9. Cutnell and Johnson, Chap 9, problem 50
10. Cutnell and Johnson, Chap 9, problem 58
11. Cutnell and Johnson, Chap 9, problem 71

12. The moment of inertia of a pyramid of density rho, height H and bottom side length L, spinning around its central axis, is

                         1               4
                   I =  --- * rho * H * L 
                         6
    

    • What is the moment of inertia of the Great Pyramid of Cheops?

      Suppose that the Pyramid was built with a frictionless bearing at the center of its bottom layer, allowing it to spin around its center without friction. Peti the smart-aleck worker is punished for his remarks about the overseer's nose: he is assigned to rotate the pyramid once around its axis. Peti can provide a constant force of F = 100 N, and he stands at one of the bottom corners of the pyramid as he pushes.

    • What is the torque Peti provides around the central axis of the pyramid?
    • How long will it take Peti to rotate the pyramid by one complete revolution?

This page maintained by Michael Richmond. Last modified Mar 8, 1999.