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问题 填空题

在“利用单摆测重力加速度”的实验中，测出单摆摆角小于50时，完成n次全振动的时间为t，用毫米刻度尺测得摆线长为L，用螺旋测微器测得摆球直径为d．

（1）用上述物理量的符号写出测重力加速度的一般表达式：g=______；

（2）由图可知，摆球直径d的读数为______；

（3）实验中有个同学发现他测的重力加速度值总是偏大，其原因可能是______：

A．实验室处在高山上，距海平面太高

B．单摆所用的摆球太重了

C．测出n 次全振动的时间为t，误作为（n+1）次全振动的时间进行计算

D．以摆线长与摆球直径之和作为摆长来计算．

答案

（1）单摆周期T=

t
n
，单摆摆长l=L+
d
2
，由单摆周期公式T=2π
l
g
，

联立可得重力加速度为：g=4n2π2（L+

d
2
）
1
t2
；

（2）由图示螺旋测微器可知，固定刻度示数为5.5mm，

可动刻度示数为48.0×0.01mm=0.480mm，

则螺旋测微器的示数为5.5mm+0.480mm=5.980mm；

（3）A、高山重力加速度偏小，故A错误；

B、周期与摆球质量无关，摆球质量大，空气阻力可以忽略，故B错误；

C、实验中误将n次全振动计为n+1次，根据T=

t
n
求出的周期变小，g偏大，故C正确；

D、以线长加球直径作为摆长来计算，摆长偏大，根据g=

4π2L
T2
可知，测得的g应偏大，故D正确；

故选CD．

故答案为：

（1）g=4n2π2（L+

d
2
）
1
t2
 

（2）5.980mm  

（3）C、D

单项选择题

下列有关增值税一般纳税人认定登记管理规程表述正确的是( )。

A．某百货店为小规模纳税人，若当年应税销售额超过小规模纳税人标准的，应在次年4月底之前，申请办理一般纳税人认定手续

B．某符合增值税一般纳税人条件的工业企业，应在向税务机关办理开业税务登记后，10日内申请办理一般纳税人认定手续

C．某汽车修理部为小规模纳税人，若当年应税销售额超过小规模纳税人标准，应在次年1月底之前，申请办理一般纳税人认定手续

D．某企业总机构在北京，分支机构在河北，分支机构应向总机构所在地的主管税务机关申请办理一般纳税人认定登记手续
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问答题

It’s a typical Snoopy card: cheerful message, bright colors, though a little yellow and faded now. Though I’ve received fancier, more expensive card over the years, this is the only one I’ve saved. One summer, it spoke volumes to me.
I received it during the first June I faced as a widow to raise two teenage daughters alone. In all the emotional confusion of this sudden single parenthood. I was overwhelmed with, of all things, the simplest housework: leaky taps, oil changes, even barbeques (烧烤). Those had always been my husband’s jobs. I was embarrassed every time I hit my thumb with a hammer or couldn’t get the lawnmower (割草机) started.
My uncertain attempts only fueled the fear inside me: How could I be both a father and mother to my girls Clearly, I lacked the tools and skills.
On this particular morning, my girls pushed me into the living room to see something. (I prayed it wasn’t another repair job. ) The "something" turned out to be an envelope and several wrapped bundles on the carpet. My puzzlement must have been plain as I gazed from the colorful packages to my daughters’ bright faces.
"Go ahead! Open them! "They urged. As I unwrapped the packages, I discovered a small barbecue grill(烧烤架) and all the necessary objects including a green kitchen glove with a frog pattern on it.
"But why " I asked.
"Happy Father’s Day! " they shouted together.
"Moms don’t get presents on Father’s Day. " I protested.
"You forgot to open the card. " Jane reminded. I pulled it from the envelope. There sat Snoopy, on top of his dog house, merrily wishing me a Happy Father’s Day. "Because," the girls said, "you’ve been a father and mother to us. Why shouldn’t you be remembered on Father’ s Day "
As I fought back tears, I realized they were right, I wanted to be a "professional" dad, who had the latest tools and knew all the tricks of the trade. The girls only wanted a parent they could count on to be there, day after day, performing repeatedly the maintenance tasks of basic care and love.
The girls are grown now, and they still send me Father’s Day cards, but none of those cards means as: much to me as that first one. Its simple message told me being a great parent didn’t require any special tools at all -just a willing worker.
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