题干

只要留心,利用身边的生活用品可以做不少物理小实验.如图26所示,塑料吸管与纸巾摩擦后会吸引小泡沫,说明吸管带了电.那么用纸巾摩擦过的塑料吸管带的是正电还是负电呢?给你玻璃棒.丝绸.橡胶棒.毛皮.塑料吸管.纸巾和细线,请设计一个可行的实验方案对此问题进行探究.



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实验方案一:操作方法:先用细线将与纸巾摩擦过的塑料吸管悬挂起来,再将用丝绸摩擦过的玻璃棒靠近塑料吸管.分析论证:若吸管与玻璃棒相互吸引,说明吸管带负电;若吸管与玻璃棒相互排斥,说明吸管带正电.

实验方案二:操作方法:先用细线将与纸巾摩擦过的塑料吸管悬挂起来,再将用毛皮摩擦过的橡胶棒靠近塑料吸管.分析论证:若吸管与橡胶棒相互吸引,说明吸管带正电;若吸管与橡胶棒相互排斥,说明吸管带负电.

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    Reaching Out to a New Friend in Starbucks

    I'm a single mom looking for a job.One morning I had grabbed my favorite spot at a local Starbucks and was going through the newspaper when I noticed a man in ragged clothing looking really untidy.I felt led to speak to this man and so I did.

    I learned that he was homeless and just wandered from place to place.Starbucks was nice enough to allow him to come in from the cold or the heat depending on the day.I also learned that he used to be an architect,but as we spoke I saw more and more that he wasn't at the fullest of mental capabilities,which made me even more upset that he didn't have a place to go.

    I sat with this man for a very long time in Starbucks calling different clinics,hospitals,shelters,police departments.He even gave me a beat up business card of a gentleman saying that was his son's phone number.It was an out-of-state number,but I called anyway but was not able to reach him.Unfortunately,all the places I called were unable to take him.

    I asked him if he was hungry and he said yes,so I went down the street to a deli(熟食店)and ordered a sandwich and drink.When I got back,my new-found friend became angry for a reason I was not aware of or maybe it was some sort of mental disturbance.All I could do was set the sandwich down and told him that I'll leave it there for him if he wanted it and I left.I walked around town for a couple of minutes and then headed back to see if he was still there.

    A man who was sitting in Starbucks most of the time when I was there came out and told me that the man ate the sandwich and that he was touched that I had sat with him like I did.It seems to me that no matter whether something goes awry(非正常的)on the surface,there is always something beautiful at a deeper level.

    I still remember my friend.I looked for him every time I was in town,but that was the last time I saw him.I hope that I had provided some glimmer of hope that he was not forgotten.