2、在正交坐标系中,设平面图形对y轴和z轴的惯性矩分别为Iy和Iz,则图形对坐标原点的极惯性矩为IP=Iy²+Iz²。
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3、若一对正交坐标轴中,其中有一轴为图形的对称轴,则图形对这对轴的惯性积一定为零。
A. 对
B. 错
平面图形对于其形心主轴的静矩和惯性积均为零,但极惯性矩一定不等于零。
A. 对
B. 错
A: I’ve come across some dates in my reading and each of them refers to some important events. Suppose I give you a few dates and you’ll try to guess what dates they are.B: OKA: ___________________________________B:Oh, that was the day when Columbus first landed in America.
5、图形对某一轴的静矩为零,则该轴必定通过图形的形心。
A. 对
B. 错