您所在的当前位置：高中物理试题 >

机车启动

> （6分）质量为1 kg的物体从高处自由落下，在下落的头2 s内重力对物体做的功是 J，这2 s内重力做功的平均功率是 w．2 s末重力对物体做功的瞬时功率是 w．

问题：

发布时间：2024-09-11

（6分）质量为1 kg的物体从高处自由落下，在下落的头2 s内重力对物体做的功是 J，这2 s内重力做功的平均功率是 w．2 s末重力对物体做功的瞬时功率是 w．

参考答案：

提问用户：sn***Jhd

可能感兴趣的题目：

1 You don’t think he is an interesting person, ________? A. do you B. don’t you C. is he D. isn’t he
2 2011年10月31日，中国在北京召集一次有老挝、缅甸、泰国安全高官参与的会议，试图推动在湄公河流域建立一套多边的安全机制。这表明 [ ] ①在区域安全上三国有着共同的利益 ②和平与发展是世界的主题 ③安全机制建立有利于维护区域稳定与和平 ④中国、老挝、泰国国家利益趋于一致 A．①②③ B．②③④ C．①③④ D．①②④
3 For high school leavers starting out in the working world，it is very important to learn particular skills and practice how to behave in an interview or how to find all internship(实习)．In some countries，schools have programs to help students onto the path to work．In the Unites States，however，such programs are still few and far between． Research shows that if high schools provide career-related courses，students are likely to get higher earnings in later years．The students are more likely to stay in school，graduate and go on to higher education． In Germany，students as young as 13 and 14 are expected to do internships．German companies work with schools to make sure that young people get the education they need for future employment． But in America, education reform programs focus on how well students do in exams instead of bringing them into contact with the working world．Harvard Education school professor Robert Schwartz has criticized education reformers for trying to place all graduates directly on the four-year college track．Schwartz argued that this approach leaves the country’s most vulnerable(易受影响的)kids with no jobs and no skills． Schwartz believed that the best career programs encourage kids to go for higher education while also teaching them valuable practical skills at high school．James Madison High School in New York，for example，encourages students to choose classes on career—based courses．The school then helps them gain on—the-job experience in those fields while they’re still at high school． However，even for teens whose schools encourage them to connect with work，the job market is daunting．In the US，unemployment rates for 16-to 19-year-olds are above 20 percent for the third summer in a row． “The risk is that if teenagers miss out on the Summer job experience，they become part of this generation of teens who had trouble in landing a job，”said Michael，a researcher in the US. 小题1:In the author’s opinion, American high school leavers__________. A．have enough career-related courses B．need more career advice from their schools C．perform better in exams than German students D．can get higher earnings in later years 小题2:According to Robert Schwartz，_________. A．there is no need for kids to go for higher education in the US B．students should get contact with the working world at high school C．education reform should focus on students’ performance in exams D．teenagers in the US can’t miss out on the summer job experience 小题3:What can be inferred from the text? A．Unemployment rates for US teenagers remain high at the moment. B．Students with career—based courses never have problems finding a job. C．US companies work with schools to prepare young people for future employment. D．High school leavers with no practical skills can’t find a job absolutely 小题4:What’s the main idea of the text? A．Arguments about recent US education reform. B．Tips on finding jobs for high school leavers. C．The lack of career—based courses in US high schools. D．Advice for American high school leavers. 小题5:The underlined word “daunting” in Paragraph 6 most probably means___________. A．discouraging B．interesting C．creative D．unbearable
4 下列实验操作顺序或方法正确的是 A．把苯和浓溴水混合后加入FeBr3可制溴苯 B．浓硫酸与浓硝酸混合冷却后，边滴入苯边振荡，在60℃水浴中加热可制硝基苯 C．乙烷中混有乙烯，通入氢气与乙烯反应可达到除杂的目的 D．乙烯通入水中可制得酒精
5 血糖的来源不包括： [ ] A．食物中的糖类物质的消化和吸收 B．肝糖元分解成葡萄糖 C．肌糖元分解成葡萄糖 D．其它物质转变成葡萄糖
6 In order to look after her sick mother, she asked for a month"s _____. [ ] A. holiday B. vacation C. leave D. rest
7 Finally they agreed ____ the terms of the contract. A．on B．to C．with D．at
8 以下几种运动中，不属于匀变速运动的是（　　） A．匀速圆周运动 B．平抛运动 C．竖直上抛运动 D．自由落体运动
9 盛有同种液体的连通器在斜面上静止时，情况正确的是 A. B. C.
10 交通运输的现代化是国家兴旺发达的重要标志之一。中国城市交通发展日新月异，但是也存在着不少问题，下列表述符合我国城市交通现状的是（） ①道路承载力低，人均道路面积较少 ②机动车增长速度过慢 ③交通管理水平较高 ④交通发展战略缺乏科学统筹 A．①② B．②③ C．③④ D．①④