The internal force of any structure is zero if it is not subjected to external loads.
A: 正确
B: 错误
A: 正确
B: 错误
举一反三
- The internal force of any structure is zero if it is not subjected to external loads.
- The magnitude of the internal force of a bar depends on not only the external force but also the shape of its cross section. A: 正确 B: 错误
- When member is subjected to the eccentric loads, the wrong description of neutral axis is ( ). A: The position of the neutral axis is independent of external forces and eccentricity B: The neutral axis and the point of the external force are on opposite sides of the cross section centroid respectively C: The neutral axis is related to the shape and size of the section D: The closer the external force point is to the centroid, the farther the neutral axis is from the centroid
- In operation, the connecting rod is subjected to both ( ) and ( ) .（ ） A: inertia loads B: centrifugal force C: gravity D: gas pressure
- 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.