第六章单元测试
- If the velocity of a moving point which is doing plane curvilinear motion is constant, the velocity vector is perpendicular to the acceleration vector. （ ）
The right angle rigid bar OAB at the instant shown in the figure has ω=2rad/s and α=5rad/s2. If OA=40cm, AB=30cm, the tangential acceleration and normal acceleration of point B are（ ）.
As shown in the figure, given AB∥O1O2, AB=O1O2=L, AO1=BO2=r, ABCD is a rectangular plate, and AD=BC=b, AO1 rod rotates around the fixed axis O1 at a uniform angular velocity ω, then the velocity and acceleration of the center of gravity C1 of the rectangular plate are （ ）.
The gear with radius R rotates around the fixed axis O, and drives the rack AB to move. Given that the angular velocity of gear is ω and the angular acceleration of gear is α at the instant shown as figure. Point C on the gear is in contact with point C' on the rack, then the acceleration of point C and the acceleration of point C' are （ ）.
The square plate ABCD is rotating around a fixed axis, and the rotational axis is perpendicular to the plate surface. The velocity of point A is vA=10cm/s and its acceleration is
. The directions are shown in the figure. Then the angular velocity of the square plate is （ ）.
A:对 B:错
答案:对
A:250 m/s2, 200 m/s2 B:250 m/s2, 250 m/s2 C:200 m/s2, 200 m/s2 D:200 m/s2, 250 m/s2
A:v=rω, a=rω2 B:v=rω/2, a=rω2 C:v=rω, a=rω2/2 D:v=lω, a=lω2
A:
B:
C:
D:
A:4rad/s B:1rad/s C:2rad/s D:3rad/s
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