Which forces belong to external forces().
A: spring force
B: damper force
C: actuator force
D: gravity force
A: spring force
B: damper force
C: actuator force
D: gravity force
举一反三
- Among the following forces, there are surface force （ ） A: gravity B: friction C: pressure D: surface tension E: inertial force
- Among the following forces, there is body force A: friction B: pressure C: surface tension D: inertial force
- Which of the following expressions is not correct (不正确)? A: If a system is only acted by conservative forces （保守力）, the mechanical energy（机械能）must be conserved （守恒）. B: If net external force is zero then the linear momentum of the system must be conserved. C: If net external force is zero, then the mechanical energy of a system must be conserved. D: If net external force is zero, then the mechanical energy of a system may not be conserved.
- The internal forces in a thin plate under bending deformation include: A: bending moment B: twisting moment C: shear force D: axial force
- Which of the following is not an external force of change?