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问题 计算题

（12分）如图，传送带与地面倾角为37°，AB长16m，传送带以10m/s的速率逆时针转动，在带上A端无初速的放一质量为0.5kg物体，它与带间的动摩擦因数为0.5，试分析物体从A到B做何运动；并求出从A运动到B所需时间？

答案

2s

开始运动时物体向下做匀加速直线运动①

②

③

加速到与带同速的时间t1： ④

此时运动位移： 

第二阶段由于，故物体继续向下做匀加速直线运动⑾

⑥

              ⑦

       ⑧

         ⑨

解得             ⑩

本题考查力与运动的关系，物体由静止放到传送带时，由于两者速度不同，肯定要发生相对滑动，物体所受滑动摩擦力沿斜面向下，当物体速度增大到与传送带速度相同时需要判断重力沿斜面向下的分力与最大静摩擦力的大小关系，从而判断以后的运动过程

点评：在求解多过程问题中，把多过程问题拆分成几小段可独立分析的过程，这样就把复杂的模型变得简单，本题中先根据相对运动判断摩擦力方向，从而判断物体的运动性质，当物体速度增大到与传送带速度时，要先判断重力沿斜面向下的分力与最大静摩擦力的大小关系，从而判断物体是静止的还是继续以另一个加速度加速运动的情况

完形填空
完形填空。
     In a small town in France, there was a farmer who lived alone. Every day he  1  a pound of butter to his
neighbor, who was a baker, One day the baker decided to  2  the butter to see if he was getting a pound.
After he weighed it, he found that he wasn't. The baker then took  3  farmer to the judge (法官).
     The judge asked the farmer if he had any way to weigh the butler. The farmer replied."I am so  4  that I
do not have enough money to buy anything to weigh it,  5  I do have a kind of scale (天平)." The judge asked,
"Then how do you weigh the buttery" The farmer replied,"Before the baker started buying butler from  6 , I
had bought bread from him. So now every time when I bring home the bread from the baker, I put it On the
scale and give him the butter of the same weight,"
    We  7  what we give to Others in life. Whenever you take action, ask yourself this  8 , "Am I honest?"
     Honesty or dishonesty can become a  9 . Some dishonest people can lie (说谎) without a red face. Others
lie so much that they do not even  10  what the truth is any more. But who is it bad for? As a matter of fact,
those who lie will hurt themselves by their own dishonest
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单项选择题

根据《MARPOL73/78》附则Ⅴ的规定，下列叙述哪项有误（）。

A．在特殊区域内外，一切塑料制品均不得投弃入海

B．在特殊区域内，一切塑料制品和其他垃圾不得处理入海

C．在特殊区域外，一切塑料制品和其他垃圾不得处理入海

D．食品废弃物能在距最近陆地12nmile以外的任何地方处理入海
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