If the normal stress on the cross section of the axial tensile rod is σ, then the normal stress and shear stress on the 45° degrees section are .
If the normal stress on the cross section of the axial tensile rod is σ, then the normal stress and shear stress on the 45° degrees section are .
connecting Rod
connecting Rod
The lower end of each piston rod is reduced in diameter to fit a bore in （）， this being secured to the piston rod by a nut.
The lower end of each piston rod is reduced in diameter to fit a bore in （）， this being secured to the piston rod by a nut.
理想运算放大器______。 A: Au为∞，rid为0，rod为∞ B: Au为∞，rid为∞，rod为0 C: Au为∞，rid为∞，rod为∞ D: 以上都不对
理想运算放大器______。 A: Au为∞，rid为0，rod为∞ B: Au为∞，rid为∞，rod为0 C: Au为∞，rid为∞，rod为∞ D: 以上都不对
如图，已知直线AC、BD是异面直线，AC⊥CD，BD⊥CD，且AB=2，CD=1，则直线AB与CD的夹角大小为（ ） A: 30° B: 45° C: 60° D: 75°
如图，已知直线AC、BD是异面直线，AC⊥CD，BD⊥CD，且AB=2，CD=1，则直线AB与CD的夹角大小为（ ） A: 30° B: 45° C: 60° D: 75°
The outside diameter of the pipe is （） the diameter of the bore of the piston rod， the result being that an annular space formed between the piston rod and the pipe.
The outside diameter of the pipe is （） the diameter of the bore of the piston rod， the result being that an annular space formed between the piston rod and the pipe.
The lightning rod is one of his useful _______________________.
The lightning rod is one of his useful _______________________.
The maximum shear stress in the rod in tension and compression is 40MPa, then the maximum normal stress in the rod is equal to . A: 80MPa B: 40MPa C: 60MPa D: 56.6MPa
The maximum shear stress in the rod in tension and compression is 40MPa, then the maximum normal stress in the rod is equal to . A: 80MPa B: 40MPa C: 60MPa D: 56.6MPa
The small end of the connecting rod is attached to the piston with a （）.
The small end of the connecting rod is attached to the piston with a （）.
图示杆件结构支座D处的约束反力为______。 A: B: A．，方向与CD杆成45°角 C: B．，方向与CD杆成45°角 D: C．，方向竖直向上 E: D．，方向竖直向上
图示杆件结构支座D处的约束反力为______。 A: B: A．，方向与CD杆成45°角 C: B．，方向与CD杆成45°角 D: C．，方向竖直向上 E: D．，方向竖直向上