小弟有三题普物想请教 希望能有强者解答，要有计算过程和解释 1.A uniform thin wire is bent into a semicircle of radius r. Determine the coordinates of its center of mass with recpect to an origin of coordinates at the center of the ''full'' circle. 2.A centrifuge rotor is accelerated from rest to 2000 rpm in 30s. (a) What is its average angular acceleration? (b) Through how many revolutions has the centrifuge rotor turned during its acceleration period, assuming constant angular acceleration? 3.A bullet of a mass m moving with velocity v strikes and becomes embedded at the edge of a cylinder of mass M and radius R0. The cylinder, initially at rest ,begins to rotate about its symmetry axis,which remains fixed in position.Assuming no frictional torque,what is the angular velocity of the cylinder after this collision?What is the change in kinetic energy? 感谢耐心阅读 谢谢回答 微薄P币以表心意 -- http://www.wretch.cc/blog/ib61632003 --

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