在利用自由落体来验证机械能守恒定律的实验中,所用的打点计时器的交流电源的频率为5

题型:问答题

问题:

在利用自由落体来验证机械能守恒定律的实验中,所用的打点计时器的交流电源的频率为50Hz,每4个点之间的时间间隔为一个计时单位,计为T,每一次测量中,(用直尺)依次测量并记录下第4点,第7点,第10点,第13点及模糊不清的第1点的位置.用这些数据算出各点到模糊的第1点的距离分别为d1=1.80cm,d2=7.10cm,d3=15.80cm,d4=28.10cm,要求由上述数据求出落体通过第7点,第10点相应位置时的即使速度v1,v2.(第1点并非就是起始点)v1,v2的计算公式分别是:v1=______ v2=______.数值大小分别是:v1=______ v2=______.

考点:实验:验证机械能守恒定律
题型:问答题

阅读理解。

     Shopping on the Internet is becoming more and more popular. Why do people use the Internet to shop?

Some people say it is more convenient. They don't have to leave their homes to order something; they can

shop for anything they want at any time; they can find things for sale that they can't find in the stores near

their homes. Still other people say they can find better prices on the Internet.

     If you want to buy something on the Internet, you need a credit (信用) card. You have to type your

credit card number and information on the website (网页) and send them to the store over the Internet. You

have to be sure that the store will not use your information in the wrong way. You don't want someone to

get your credit card number, so be careful with it, beause people sometimes steal (窃取) credit card numbers

from stores.

     The Internet is also a good place to go window-shopping. Window-shopping is when you look at the

things for sale in a store, but don't plan to buy anything. In window-shopping you can see what kinds of things

you are able to get and how much they cost. Some stores like Ross Stores have a website for information

about their stores, but not for shopping. Some stores have a website for information about their stores, and

can shop on-line there, such as Office Depot, Payless Shoe Source, Safeway. Some stores like Amazon. com

are only for on-line shopping.

1. Some people use the Internet to shop because ________.

A. they can sleep all day long

B. they want to leave their homes

C. they want to play with their friends

D. they can get things with less money

2. The Chinese meaning of the word "convenient" in this passage is "________".

A. 时髦的

B. 较近的

C. 方便的

D. 可用的

3. If you want to shop on the Internet, you need ________.

A. an ID card

B. a credit card

C. an IC card

D. a room card

4. Which of the following is NOT true according to the passage?

A. You can shop on-line at www.officedepot.com

B. You cannot shop on-line at www.rossstores.com

C. You can only do window-shopping at www.amazon.com

D. You can do window-shopping and shop on-line at www.safeway.com

题型:问答题

功能温中行气,涩肠止泻的药物是()。

A.草豆蔻

B.肉豆蔻

C.桑螵蛸

D.海螵蛸

E.五味子

题型:问答题

句型转换。

1.昨天的天气如何?

   ________ ________  the  weather ________ yesterday?

   ________ ________ the weather yesterday?

2. I knew something about it. (改为否定句)

    I ________ ________ ________about it.

3. I decided l would buy a new car. (改为同义句)

    I ________ ________  buy a new car.

4. She hopes she can go bike riding. (改为同义句)

    She________ ________go bike riding.

题型:问答题

颢骨骨折分为____、____、____和____4种类型。

题型:问答题

挡土墙泄水孔进口处的反滤层应选用不透水材料。 ( )

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