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质量为m、长为l的均质杆OA绕O轴在铅垂平面内做定轴转动。已知某瞬时杆的角速度为ω,角加速度为α,则杆惯性力系合力的大小为( )。
A A.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818189_0_1.png"> B B.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818189_0_2.png"> C C.lmα/2 D D.lmω^2/2
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两系统均做自由振动,其固有圆频率分别为( )。
A A.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_1.png">,<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_2.png"> B B.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_3.png">,<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_4.png"> C C.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_5.png">,<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_6.png"> D D.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_7.png">,<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818191_0_8.png">
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单选
重为W的质点,由长为l的绳子连接,则单摆运动的固有圆频率为( )。
A A.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818192_0_1.png"> B B.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818192_0_2.png"> C C.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818192_0_3.png"> D D.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818192_0_4.png">
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质量为110kg的机器固定在刚度为2×10^6N/m的弹性基础上,当系统发生共振时,机器的工作频率为( )。
A A.66.7rad/s B B.95.3rad/s C C.42.6rad/s D D.134.8rad/s
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单选
半径为R,质量为m的均质圆盘由铰支座和绳约束,铰O与质心C位于水平位置。当剪断绳的瞬时,圆盘的ωO和αO分别为______;当OC转至与水平成90°时圆盘的ω和
A A.ωO=0和αO=4g/(3R);<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818202_0_1.png">和αO=2g/(3R) B B.ωO=0和αO=2g/(3R);<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818202_0_2.png">和α=0 C C.ωO=0和αO=g/(3R);<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818202_0_3.png">和α=0 D D.ωO=0和αO=4g/(3R);<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818202_0_4.png">和α=2g/(3R)
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重为P的小球系于细绳的一端,绳的另一端穿过光滑水平面上的小孔O,令小球在此水平面上沿半径为r的圆周作匀速运动,其速度为v0。如果将绳下拉,使圆周的半径减小为r/
A A.T=2Pv0^2/(gr) B B.T=8Pv0^2/(gr) C C.T=Pv0^2/(gr) D D.T=4Pv0^2/(gr)
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质量为m,半径为r的定滑轮O上绕有细绳。依靠摩擦使绳在轮上不打滑,并带动滑轮转动。绳之两端均系质量m的物块A与B。块B放置的光滑斜面倾角为α,0<α<π/2,假
A A.FT1=FT2 B B.FT1<FT2 C C.FT1>FT2 D D.只依据已知条件则不能确定
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均质等厚零件,设单位面积的质量为ρ,大圆半径为R,挖去的小圆半径为r,两圆心的距离为a,则零件对过O点并垂直于零件平面的轴的转动惯量为( )。
A A.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818200_0_1.png"> B B.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818200_0_2.png"> C C.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818200_0_3.png"> D D.<img border="0" alt="" src="https://tuku.weimei168.com/uploads/upimg/20251103/23818200_0_4.png">
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重10N的物块沿水平面滑行4m,如果摩擦系数是0.3,则重力及摩擦力各做的功是( )。
A A.40N·m,40N·m B B.0,40N·m C C.0,12N·m D D.40N·m,12N·m
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均质细杆OA,质量为m,长l。在如图所示水平位置静止释放,释放瞬时轴承O施加于杆OA的附加动反力为( )。
A A.3mg(↑) B B.3mg(↓) C C.3mg/4(↑) D D.3mg/4(↓)
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