A thin rod has a length of 0.25 m and rotates in a circle on a frictionless tabletop. The axis is perpendicular to the length of the rod at one of its ends. The rod has an angular velocity of 0.33 rad/s and a moment of inertia of 1.40 10-3 kg · m2. A bug standing on the axis decides to crawl out to the other end of the rod. When the bug (mass = 4.2 10-3 kg) gets where it's going, what is the angular velocity of the rod?

1 answer

Angular momentum after = angular momentum before

angular momentum before
= I w = 1.4*10^-3 * .33
= .462 * 10^-3

angular momentum after =
(1.4*10^-3 + 4.2*10^-3) w

so
w = .462/5.6 = .0835 rad/s