The three bars O1A, O2B and AB are pin-connected in one plane. At the position shown, O1A//O2B. In which case bar AB undergoes translation when bars O1A and O2B rotate in the plane.
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Three bars are subjected to compression as shown. If the absolute values of the maximum compressive stresses in bars 1, 2 and 3 are σmax1, σmax2 and σmax3, respectively, then their relationship should be
A、σmax1<σmax2<σmax3<br> B、σmax1<σmax2=σmax3<br> C、σmax1<σmax3<σmax2<br> D、σmax1=σmax3<σmax3<br>
Three bars are subjected to compression as shown. If the absolute values of the maximum compressive stresses in bars 1, 2 and 3 are σmax1, σmax2 and σmax3, respectively, then their relationship should be
A、σmax1<σmax2> <σmax3>
B、σmax1 <σmax2=σmax3>
C、σmax1 <σmax3> <σmax2>
D、σmax1=σmax3 <σmax3>
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B.
C.
D.
In the planar mechanism, the three bars (,and), wheeland sliderare pin-connected together. Barrotates around point. Wheelrotates without slipping on the horizontal surface. Slidermoves in vertical direction. Which statements are correct?
A、Pointis the instantaneous center for velocities of wheel.
B、Pointis the instantaneous center for velocities of bar.
C、Pointis the instantaneous center for velocities of bar.
D、Pointis the instantaneous center for velocities of bar.
在瓦特行星传动机构中,平衡杆O1A绕O1轴转动,并借连杆AB带动曲柄OB;而曲柄OB活动地装置在O轴上,如图所示。在O轴上装有齿轮Ⅰ,齿轮Ⅱ与连杆AB固连于一体。已知:O1A=0.75mm,AB=1.5m;又平衡杆的速度ω=6rad/s.求当α=60°且β=90°时,曲柄OB和齿轮Ⅰ的角速度。
图(a)所示偏心轮摇杆机构中,摇杆O1A借助弹簧压在半径为R的偏心轮C上。偏心轮C绕轴O往复摆动,从而带动摇杆绕轴O1摆动。设OC⊥OO1,时,轮C的角速度为ω,角加速度为零,θ=60°。求此时摇杆O1A的角速度ω1,和角加速度α1。
In the planar mechanism, the three bars (,and), wheeland sliderare pin-connected together. Barrotates around point. Wheelrotates without slipping on the horizontal surface. Slidermoves in vertical direction. Which statements are correct?
A、Pointis the instantaneous center for velocities of wheel.
B、Pointis the instantaneous center for velocities of bar.
C、Pointis the instantaneous center for velocities of bar.
D、Pointis the instantaneous center for velocities of bar.
In the planar mechanism, the three bars (,and), wheeland sliderare pin-connected together. Barrotates around point. Wheelrotates without slipping on the horizontal surface. Slidermoves in vertical direction. Which statements are correct?
A、Pointis the instantaneous center for velocities of wheel.
B、Pointis the instantaneous center for velocities of bar.
C、Pointis the instantaneous center for velocities of bar.
D、Pointis the instantaneous center for velocities of bar.
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