单位体积内土粒的质量，称为

A、无偿合同

B、双务合同

C、实践合同

D、无名合同

一质量为m，电量为q的粒子，从电势为的A点，在电场力的作用下运动到电势为的B点。若粒子到达B点时的速率为，则电场力做的功为（）。

A、

B、

C、

D、

A、姓名

B、性别

C、既往史

D、经济收入等基本信息

A、理论性课题

B、解释性课题

C、预测性课题

D、自选课题

1. Explain the following terminologies: The generalized Hooke's law Strain energy per unit volume, for normal and shearing stress: Incremental theories: Total strain theories: Ture stress: True strain: 2. A cubic metal, with the edge length of 200 mm, elastic modulus E = 207×1000 MPa, and Poisson’s ratio ν = 0.3, is compressed along Z direction, and the metal expands along X and Y directions. If the compression along Z direction is 200 MPa, in order to limit the expansion along X and Y directions within 0.05 mm, what is the compression should be applied along X and Y directions?