Question

A Texas cockroach of mass 0.17 kg runs counterclockwise around the rim of a lazy Susan (a circular disk mounted on a vertical axle) that has radius 15 cm, rotational inertia 4.9 ✕ 10−3 kg · m2, and frictionless bearings. The cockroach's speed (relative to the ground) is 2.0 m/s, and the lazy Susan turns clockwise with angular speed ω0 = 2.9 rad/s. The cockroach finds a bread crumb on the rim and, of course, stops. (a) What is the angular speed of the lazy Susan after the cockroach stops? rad/s (b) Is mechanical energy conserved as it stops? Yes No

Answer 1

a) From the law of conservation of angular momentum is, 'mR' +I (0.17)(2)(15×10-*)-(4.9 x 10-3)(29) 0.17x(15x102)+49x10 4.217 rad/sec b) Mechanical energy is not conserved as it stops, because the energy is transferred to the mechanical energy