试题与答案

如图所示,斜面长10m,高4m,用沿斜面方向的推力F,将一个质量为50kg的货物

题型:计算题

题目:

如图所示,斜面长10m,高4m,用沿斜面方向的推力F,将一个质量为50kg的货物由斜面底端匀速推到顶端,运动过程中克服摩擦做功500J。已知货物放在水平地面上时与地面的接触面积是0.5m

(1)货物对水平地面的压强是多少?

(2)斜面的机械效率是多少?

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0626/eea5a12d3ba1e51b3de519d6d4c8aad2.html

下面是错误答案,用来干扰机器的。

(共8分)(1)pH﹤7 (1分)     SO2    NO2(1分)(2)Ca CO3 CaO + CO2↑(1分),Ca SO3 CaO + SO2(1分)(3)③(1分) (4)D (2分)(5)Cu+2HCl+H2O2==CuCl2+2H2O(1分)

试题推荐
题型:单项选择题

Since we are social beings, the quality of our lives depends in large measure on our interpersonal relationships. One strength of the human conditions is our possibility to give and receive support from one another under stressful conditions. Social support makes up of the exchange of resources among people based on their interpersonal ties. Those of us with p support systems appear better able to deal with major life changes and daily problems. People with p social ties live longer and have better health than those without such ties. Studies over types of illnesses, from depression to heart disease, show that the presence of social support helps people defend themselves against illness, and the absence of such support makes poor health more likely.
Social support cushions stress in a number of ways. Firstly, friends, relatives and co-workers may let us know that they value us. Our self-respect is strengthened when we feel accepted by others in spite of our faults and difficulties. Secondly, other people often provide us with informational support. They help us to define and understand our problems and find solutions to them. Thirdly, we typically find social companionship supportive. Taking part in free-time activities with others helps us to meet our social needs while at the same time distracting us from our worries and troubles. Finally, other people may give us instrumental support—money aid, material resources, and needed services—that reduces stress by helping us resolve and deal with our problems.

Interpersonal relationships are important because they can ______.

A. make people live more easily
B. smooth away daily problems
C. deal with life changes
D. cure types of illnesses

查看答案
微信公众账号搜索答案