Two particles, each with mass m = 0.85 kg, are fastened to each other, and to a rotation axis at O, by two thin rods, each with length d = 5.6 cm and mass M = 1.2 kg. The combination rotates around the rotation axis with angular speed w = 0.30 rad/s. Measured about O, what are the combination's (a) rotational inertia and (b) kinetic energy?
parallel-axis theorem: I = Icom + Mh^2
rotational inertia for thin rod: I = 1/12ML^2
K = 1/2Iomega^2
The Attempt at a Solution
Inet = Irod1 + Iparticle1 + Irod2 +Iparticle2
Inet = 1/12Md^2 + Md^2 + 1/12M(2d)^2 + M(2d)^2