题干

如图所示是用细绳将质地均匀的玉石手镯吊在天花板上.请在实物图中画出手镯受到的拉力F和重力G的示意图


上一题 下一题 0.0难度 选择题 更新时间:2015-04-24 05:52:51

答案(点此获取答案解析)

解:如图所示:


同类题1

阅读理解

The World's Coolest Places

    There's nothing wrong with a relaxing week at the beach. But travel can also be an education, a step toward empathy(共鸣) and international understanding, so for those longing to escape the crowds this summer, encounter new worlds and return with a tale, here're a few little-known travel destinations I recommend.

⒈Bikini Atoll, Marshall Islands.

    This coral island in the Pacific Ocean, site of nuclear weapons tests decades ago, is now brilliantly beautiful and the deserted white-sand beaches are lined with coconut palms and scattered with seashells. The island is a reminder of the redemptive(救赎的) power of time and nature.

⒉Potosi, Bolivia.

    No city in Latin America is more beautiful than Potosi, Bolivia, where Europeans discovered a huge silver mountain centuries ago. Tourists can descend(下降) the silver mines to experience extremely hot and dusty tunnels, talk to the miners, get a glimpse of life image for Bolivians there and have new empathy for the miners.

⒊Victoria Falls, Zimbabwe.

    Maybe our family start at Victoria Falls, which wets you with spray, making Niagara Falls a backyard stream. Then we rent a car and make our way to Hwange National Park, empty of people but crowded with various animals. Zimbabwe has fewer tourists than South Africa, and there's less crime as well.

⒋Amritsar, India.

    The Golden Temple, Sikhism's holiest shrine(神殿), is a delightful place to contemplate the draw of faith. A four-century-old temple set in a lake attracts Sikhs(锡克教徒) worldwide. Walking the circuit of the lake, with your head covered, and putting up in temple buildings can be a full experience.

同类题4

枯枝落叶是土壤有机物的主要来源,下表为三地区森林枯枝落叶量和土壤有机物现存量的调查数据,则分解者的作用由强至弱依次为
 
北方森林
温带落叶林
热带雨林
枯枝落叶量(单位:t/ha)
7.5
11.5
30
土壤有机物现存量(单位:t/ha)
35
15
5