5. Problem 11.50E (HRW) Two particles, each with mass m, are fastened to each other, and to a rotation axis at O, by two thin rods, each with length l and mass M as shown in the figure. The combination rotates around the rotation axis with angular velocity . Obtain algebraic expressions for (a) the rotational inertia of the combination about O and (b) the kinetic energy of rotation about O. |
Solution: Click For PDF Version (a) As mass of each rod is m and their combined length is 2l, the moment of inertia of the rods with respect to rotation axis at O is . The moment of inertia of the two balls about O is . Therefore, the algebraic expression for the rotational inertia of the combination about O is . (b) And, the kinetic energy of rotation about O is . |