第十一章单元测试
The small ball M with weight Q is fixed on a thin homogeneous rod of length l and weight P. The other end of the rod is hinged on the roof of the car moving with v. The rod OM rotates counterclockwise around axis O at an angular velocity ω. Then the magnitudes of the momentums of the rod and the small ball at the instant shown as figure are （ ）.
Two identical homogeneous disks are placed on a smooth horizontal plane, and two same horizontal forces are applied on the different positions of the disks, respectively, so that the disks start to move from rest. The mass center of disk A moves faster. （ ）
When A particle of mass m moves in a circle at a constant speed vA=vB=v from position A to position B, the impulse of the force acting on the particle is （ ）.
The figure shows a crank-rod mechanism on the platform, which is composed of two homogeneous bars and a slider. The rod O1A rotates at a uniform angular velocity ω and given: O1A weighs P1, AB weighs P2, platform weighs Q, O1A=AB=L. Let t=0, angle =0, and the velocity of platform is zero. Excluding the mass of the slider B and the friction on the ground, the motional equation of the platform is （ ）.A homogeneous rod OA rotates around the fixed axis O with constant angular velocity ω. The mass of the rod is m and its length is L, then the magnitude of momentum of this rod is mLω/2.
A:
B:
C:
D:
答案:
A:错 B:对
A:
B:
C:
D:
A:
B:
C:
D:
A:对 B:错
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