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问题 计算题

如图所示，长L=75cm的静止直筒中有一不计大小的小球，筒与球的总质量为4千克，现对筒施加一竖直向下、大小为21牛的恒力，使筒竖直向下运动，经t=0.5秒时间，小球恰好跃出筒口。求：小球的质量。（取g=10m/s2）

答案

解：设筒与小球的总质量为M，小球的质量为m，筒在重力及恒力的共同作用下竖直向下做初速为零的匀加速运动，设加速度为a；小球做自由落体运动。设在时间t内，筒与小球的位移分别为h1、h2（球可视为质点），如图所示：

由运动学公式得：，

又有：L=h1－h2

代入数据解得：a=16m/s2

又因为筒受到重力(M－m)g和向下作用力F，据牛顿第二定律：F+(M－m)g=(M－m)a

得：

单项选择题

诚实守信是遵守会计职业道德的（）。

A.效率规则

B.基本要求

C.质量标准

D.外在要求
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阅读理解

阅读理解。

     Barefoot Traveler is a tour agent that specializes in diving holidays, tailor-made to your own needs. The

most popular destinations include Bonaire, Tobago, the Bahamas, Maldives,Oman, Seychelles and Thailand.

     Our friendly and knowledgeable staff, who are qualified divers (潜水员) themselves, will be able to advise

you on the best destinations for your requirements.

     Whether you want to learn to dive, further your diving qualifications, continue to discover the underwater

world, or simply relax on the beach, we are here' to help organize your holiday.

     We are happy to satisfy single travelers and offer special discounts (折扣).

     Group discounts are offered to groups of eight or more travelers and tailor-made packages are available for

Dive Clubs.

     We also offer a series of diving live aboard choices throughout the Caribbean. Indian Ocean and South East

Asia. Live aboards are very popular scuba (呼吸器) diving holidays for those who want to access the best

diving sites.

     Our barefoot luxury holiday brand is for those trying something a little more special, whether it's your

honeymoon, anniversary or simply for more discerning (有品位的) travelers. We have a selection of 4 and 5

star levels which are the best in luxury holidays.

1. What's the author's purpose in writing this passage?

A. To give some advice on diving.

B. To introduce the popular destinations.

C. To teach diving skills.

D. To attract tourists.

2. Which of the following is TRUE according to the passage?

A. It's impossible to be offered tailor-made packages when you join Dive Clubs.

B. Au staff are qualified divers with wide knowledge on the best diving.

C. Barefoot Traveler specializes in simple holidays.

D. Travelers can enjoy Winter Sun.

3. According to the passage, Barefoot Traveler _____.

A.is not a tour agent

B. has over 25 scuba diving liveaboard beats

C. makes the luxury holiday based on consumers' needs and desires

D. makes the luxury holiday you don't have in mind

4. The best title for this passage would be _____.

A. Welcome to Barefoot Traveler

B. A Wonderful Experience

C. Scuba Diving

D. How to Choose Destinations

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