某学生骑着自行车(可视为质点)从倾角为θ=37°的斜坡AB滑下,然后在水平地面B

题型:问答题

问题:

某学生骑着自行车(可视为质点)从倾角为θ=37°的斜坡AB滑下,然后在水平地面BC上滑行一段距离后停下,整个过程中该学生始终未蹬脚踏板,如图甲所示.自行车后架上固定一个装有墨水的容器,该容器距地面很近,每隔相等时间T滴下一滴墨水.该学生用最小刻度为cm的卷尺测得某次滑行数据如图乙所示.假定人与车这一整体在运动过程中所受阻力大小恒定.己知人和自行车总质量m=80kg,g取10m/s2,sin37°=0.6,cos37°=0.8.则T=______s,人与车在斜坡AB上运动时加速度大小a1=______m/s2,在水平地面运动时加速度大小a2=______m/s2

考点:滑动摩擦力、动摩擦因数力的合成牛顿第二定律
题型:问答题

阅读理解。

     Every morning Tom goes to work by train. He has a long way to go. So he always buys a

newspaper. It helps him to spend (消磨) the time on the train.

     Tom likes sport very much. One morning on the train he is reading something about the football

match. So he forgets to get off the train at his station (车站). He doesn't know it. When he finishes

reading, he looks out of the window. It's far from his station. He gets off at the next station. He has

to go back by train. Of course, he is late for work.

1. Tom goes to work by ______.  

A. train    

B. bike    

C. car        

D. bus

2. Tom likes ______.

A. reading    

B. sport        

C. music      

D. working

3. Tom's work place is ______ his home.

A. near      

B. far from    

C. beside    

D. behind

4. What does Tom buy every morning?

A. a book    

B. a football    

C. a hamburger    

D. a newspaper

5. Where does he get off the train at last?

A. the right station        

B. the next station to his work place

C. before the train station    

D. we don't know

题型:问答题

“民以食为天”。下列过程中发生了化学变化的是[ ]

A.淘米

B.洗菜

C.天然气燃烧

D.苹果榨汁

题型:问答题

船舶定线制推荐给()使用;

A.所有的船舶使用,除非另有说明

B.所有的机动船

C.所有深吃水的船舶

D.所有操纵困难的船舶

题型:问答题

盘铣刀主要用于加工( )

A.平面
B.圆柱面
C.沟槽
D.成形面

题型:问答题

在系统分析过程中,编写数据字典时,各成分的命名和编号必须依据()

A.数据流程图

B.决策表

C.数据结构

D.U/C矩阵

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