The hour hand and the minute hand of Big Ben, the Elizabeth Tower clock in London, are 2.70 m and 4.50 m long and have masses of 60.0 kg and 100 kg, respectively (see Fig. P10.49). (a) Determine the total torque due to the weight of these hands about the axis of rotation when the time reads (i) 3:00, (ii) 5:15, (iii) 6:00, (iv) 8:20, and (v) 9:45. (You may model the hands as long, thin, uniform rods.) (b) Determine all times when the total torque about the axis of rotation is zero. Determine the times to the nearest second, solving a transcendental equation numerically.

Ch.9:CenterofMassandMomentum A. ChapterGoals • Studyofwhatiscenterofmass • Studyofwhatislinearmomentumandwhenitconserves • StudyofwhatisImpulseandwhatisimpulse-momentum theorem • Studyofwhatiscollisionandwhatareelas▯c,inelas▯c, andperfectinelas▯ccollisions • Studyofwhatthemechanismforrocketpropulsion Ch.9:CenterofMassandMomentum B.CenterofMass(COM) • Thecenterofmassofasystemofpar▯clesisthepointthat movesasthough(1)allofthesystem’smasswere concentratedthereand(2)allexternalforceswereapplied there. • Figureshowsthemo▯on ofabaseballbatandits centerofmass(blackdot). Ch.9:CenterofMassandM