问题 问答题 计算题

某液压系统采用限压式变量泵供油,调定后泵的特性曲线如图15所示,已知泵流量qmax=40L/min,限定压力pB=3×106MPa,截止压力PC=5×106MPa,液压缸的有效面积A1=5×10-3m2,A2=2.5×10-3m2,试确定:

(1)负载为2×104N时,活塞运动速度v。

(2)此时液压缸的输出功率P。

(3)活塞快退时的速度v退

答案

参考答案:

(1)v=4m/min

(2)P=1.33kW

(3)v退=16m/min

问答题
阅读理解

阅读理解

     Customs are social habits. They have been handed down through generations  among groups, social

classes, etc. Customs can be described as ways of doing things. They are particularly strong in social

practices on the occasions  of births, marriages and deaths.

     In China, these days, some people in cities are learning from Western customs. For example, some

brides dress in the long white dress that is usual bridal wear in many Western countries.

     Every people has special customs for New Year. The Han people have many interesting Spring

Festival customs. And now, quite a number of people living in the cities have followed the Western

customs of sending New Year greeting cards for January 1st.

     One interesting custom in China is that mothers wrap up their babies tightly.This is not the custom in

Western countries, where babies are usually dressed in loose garments.

1. Which of the following statement is right?

A. Customs have been formed during a short time

B. Customs have been formed little by little

C. Customs have been quickly formed and changed

D. Customs have never been changed

2. In this passage, the word "people" is      .

A. 人们      

B. 人类      

C. 民族      

D. 大家

3. How do the Chinese young people learn from Western countries at their marriages?

A. The brides(新娘)have on the white clothes.

B. Men wear the white coats.

C. Their parents all have attended their marriages.

D. Their marriages are only held in Church.

4. From this passage we know      .

A. the people all over China spend New Year in the same way

B. people in the villages and cities send New Year greeting ny e-mail each other

C. each people has his special custom for New Year

D. most of Chinese people like to spend Spring Festival.

5. The difference about clothing between Chinese and Western babies is that      .

A. Chinese babies are usually dressed in new clothes

B. Western mothers are used to dressing their babies in colourful clothes

C. Western babies are dressed in bigger clothes while Chinese babies are usually wrapped

D. Chinese babies have more clothes than Western babies