【简答题】9-31 已知两方向同频率的简谐振动的运动方程分别为 , ,式中 的单位为m,t的单位为s.求: (1)合振动的振幅及初相; (2)若有另一同方向同频率的简谐振动 ,式中 的单位为m,t的单位为s,则 为多少时, 的振幅最大?又 为多少时 , 的振幅最小?
【单选题】He is now a teacher and a ( ) member of the community.
【简答题】Mr Green is our foreign teacher . He is a good teacher . He often helps us a lot .And he is nice to every student . His lessons are very interesting . We usually have fun in his lessons . We all like ...
【简答题】两同方向同频率简谐振动的合成,已知振动方程分别为 则合振动的振幅为 cm
【简答题】两同方向同频率简谐振动的合成,已知振动方程分别为 则合振动的振幅为 cm
【简答题】根据短文内容,选择正确答案。 Sam is a teacher of maths. He is not young, but he is not old. He is 40 years old. He has a round (圆的) face and black hair. He is short. There are forty students in his class. They all ...
【简答题】Mr Green is our foreign(外国的)teacher.He is a good teacher.He often helps us a lot.And he is nice to every student.His lessons are very interesting.We usually have fun in his lessons.We all like him. He...
【多选题】如果计入表面态的影响,当表面态为施主态,且态密度足够大时,关于异质结能带结构的描述,正确的是?
A.
此时异质结界面两边的状态完全由界面态电荷决定,与功函数等没有关系。
B.
对于 n 型半导体,在半导体表面形成很薄的多子积累层。
C.
对于 p 型半导体,在半导体表面形成很厚的耗尽层。
D.
对于n型半导体, 在半导体表面形成很厚的耗尽层。
E.
对于p 型半导体, 在半导体表面形成很薄的多子积累层。
【多选题】梁的腹板局部稳定不满足要求时可以采取( )方法