12-1计算例12-1的蜗杆和蜗轮的几何尺寸。 12-2如图所示,蜗杆主动,T1=20Nm,m=4mm,z1=2,d1=50mm,蜗轮齿数z2=50,传动的啮合效率n=0.75。试确定:()蜗轮的转向(2)蜗杆与蜗轮上作用力的大小和方向

I If f(t)=100 for 04.(a) Calculate v at t=T/4.(b) Find the average power delivered by this waveform to a 5Q2 resistor 3 Let v(t)=3-3 cos(100 t-40)+4 sin(200 T t-10)+2.5 cos 300 tt V Find: (a)the average value Var;(b)the rms value V;(c)the period T; (d)v(18ms)

1.气相反应A+2B>2C,A和B的初始压力分别为p(A)和p(B)应开始时并无C若p为体系的总压力,当时间 为t时,A的分压为: () p(A)-p(B) ()p-2p(A) (C)p-p(B) (D) 2(p-p(A)-p(B)

Inertial reference frames In the previous lecture, we derived an expression that related the accelerations observed using two reference frames, A and B, which are in relative motion with respect to each other. aA =aB+(aA/ B)'y'' 22 x (DA/ B) 'y'2'+ TA/B+ X TA/B). (1) Here, aA is the acceleration of particle A observed by one observer, and

We have seen that the work done by a force F on a particle is given by dw =. dr. If the work done by F, when the particle moves from any position TI to any position T2, can be expressed as, W12=fdr=-(V(r2)-V(1)=V-v2, (1) then we say that the force is conservative. In the above expression, the scalar

第一章总论 一、判断题 1.2.3.4.V5.V 6.√7.8.V9.X 二、单项选择题 1.A2.B3C4.C5.A6.B 7.B。8.D9.A10。B11.C12.B

1.NH4HS(s)和任意量的NH3(g)及H2S(g)达平衡时,有: (A)C=2,=2,f=2 (B)C=1,=2,f=1 (C)C=2,=3,f=2 (D)C=3,=2,f=3

第1章数据库原理及基本概念 1.填空题 (1)数据及数据之间的联系 (2) DBMS (3)数据库 (4)记录 (5)概念设计、逻辑设计 2.选择题 (1)A(2)A、C、D(3)A

一、回答下列问题:(每题6分) (1)作用力与反作用力是一对平衡力吗? (2)图a中所示三铰拱架上的作用力F,可否依据力的可传性原理把它移到D点?为什么?

一、单项选择题。(共14分,每小题2分) 1.下列哪个符号不能作为VB中的变量名?() (A)wash (B)CET4 (C)fh (D)a[3] 2.函数Int(6*RND)+1的值是在哪个范围内的整数?() (A)0,6 (B)[0,7 (C)1,6