欧美日韩精品一区,91在线国产观看,国产免费黄色

精英家教網(wǎng) > 高中地理 > 題目詳情

【題目】如圖所示，兩根相距為L＝1m的足夠長的平行光滑金屬導(dǎo)軌，位于水平的xOy平面內(nèi)，一端接有阻值為R＝6Ω的電阻。在x>0的一側(cè)存在垂直紙面向里的磁場(chǎng)，磁感應(yīng)強(qiáng)度B只隨t的增大而增大，且它們間的關(guān)系為B＝kt，其中k＝4T/s。一質(zhì)量為m＝0．5kg的金屬桿與金屬導(dǎo)軌垂直，可在導(dǎo)軌上滑動(dòng)，當(dāng)t＝0時(shí)金屬桿靜止于x＝0處，有一大小可調(diào)節(jié)的外力F作用于金屬桿，使金屬桿以恒定加速度a＝2m/s2沿x軸正向做勻加速直線運(yùn)動(dòng)。除電阻R以外其余電阻都可以忽略不計(jì)。求：當(dāng)t＝4s時(shí)施加于金屬桿上的外力為多大。

【答案】513N

【解析】t＝4s時(shí)，金屬桿移動(dòng)的位移x＝at2＝×2×16m＝16m

此時(shí)的速度v＝at＝2×4m/s＝8m/s

切割產(chǎn)生的動(dòng)生電動(dòng)勢(shì)E1＝BLv＝ktLv＝4×4×1×8V＝128V

磁場(chǎng)變化產(chǎn)生的感生電動(dòng)勢(shì)E2＝Lx＝4×1×16V＝64V

根據(jù)楞次定律和右手定則知，兩個(gè)電動(dòng)勢(shì)的方向相同

則總電動(dòng)勢(shì)E＝E1＋E2＝192V

則感應(yīng)電流的大小I＝＝32A

根據(jù)牛頓第二定律得，F(xiàn)－BIL＝ma

解得F＝BIL＋ma＝4×4×32×1＋0．5×2N＝513N

練習(xí)冊(cè)系列答案

名校課堂系列答案

西城學(xué)科專項(xiàng)測(cè)試系列答案

小考必做系列答案

小考實(shí)戰(zhàn)系列答案

小考復(fù)習(xí)精要系列答案

小考總動(dòng)員系列答案

小升初必備沖刺48天系列答案

68所名校圖書小升初高分奪冠真卷系列答案

伴你成長周周練月月測(cè)系列答案

小升初金卷導(dǎo)練系列答案

年級(jí)	高中課程	年級(jí)	初中課程
高一	高一免費(fèi)課程推薦！	初一	初一免費(fèi)課程推薦！
高二	高二免費(fèi)課程推薦！	初二	初二免費(fèi)課程推薦！
高三	高三免費(fèi)課程推薦！	初三	初三免費(fèi)課程推薦！
更多初中、高中輔導(dǎo)課程推薦,點(diǎn)擊進(jìn)入>>

相關(guān)習(xí)題

科目：高中地理 來源： 題型：

【題目】短文改錯(cuò)

假定英語課上老師要求同桌之間交換修改作文，請(qǐng)你修改你同桌寫的以下作文。文中共有10處語言錯(cuò)誤，每句中最多有兩處。每處錯(cuò)誤僅涉及一個(gè)單詞的增加、刪除或修改。

增加：在缺詞處加一個(gè)漏字符號(hào)(/\)，并在其下面寫出該加的詞；

刪除：把多余的詞用斜線(\)劃掉；

修改：在錯(cuò)詞下畫一橫線，并在該詞下面寫出修改后的詞。

注意：1. 每處錯(cuò)誤及其修改均僅限一詞；

2. 只允許修改10處，多者(從第11處起)不計(jì)分。

Last weekend, my classmate and I went on a camping trip near the river. It was not long distance, so we chose to get here by bike.

We started with early in the morning. On the way, we talked about that we saw around. It takes about half an hour to get to the place. On arriving, some girls sat down, had her breakfast and listened to the birds sings. Some admired the river while others drew pictures. My friends and I found a quietly place and went fishing. To our surprise, we got much fishes.

Time passed so quickly and we had to say goodbye. I enjoyed the pleasant or exciting trip.

查看答案和解析>>

科目：高中地理 來源： 題型：

【題目】A

The first ancient Olympic Games for which we still have written records were held in 776 BC. Coroebus won the only event at the Olympics. This made him the very first Olympic champion in history. Then they grew and continued to be played every four years. In 393 AD, the Roman emperor Theodosius Ⅰ, a Christian, announced to end the Games because of their pagan (異教的) influences.

About 1,500 years later, a young Frenchman named Pierre de Coubertin began their revival (恢復(fù)). In 1892 Coubertin first brought forward his idea to revive the Olympic Games but failed.

Two years later, Coubertin organized a meeting with 79 delegates (代表) who represented nine countries. At this meeting he got what he wanted. All the delegates at the conference voted for the Olympic Games. They also decided to have Coubertin set up an international committee to organize the Games. This committee became the International Olympic Committee (IOC) and Demetrious Vikelas from Greece was selected to be its first president. Athens was chosen for the revival of the Olympic Games and the planning was begun.

The very first modern Olympic Games opened in the first week of April, 1896. Since the Greek government had been unable to afford a stadium, a rich Greek architect, Georgios Averoff, donated one million drachmas (over $100,000) to repair the Panathenaic Stadium, originally built in 330 BC.

Since the Games were not well publicized internationally, contestants (選手) were not nationally chosen but rather came individually and at their own expense. Some contestants were tourists who happened to be in the area during the Games.

【1】What would be the best title for the passage?

A. The History of the Olympics

B. How Coubertin Set up IOC

C. The First Modern Olympic Games

D. Great Changes in the Olympic Games

【2】 Coubertin held a most important meeting with 79 delegates in______________.

A. 1500 B. 1892

C. 1894 D. 1896

【3】 Who offered money to help the first modern Olympic Games?

A. Demetrious Vikelas.

B. Coroebus.

C. Pierre de Coubertin.

D. Georgios Averoff.

【4】At the first modern Olympic Games, ______________.

A. winners were given money as prize

B. IOC invited contestants to tour Greece

C. there were no strict rules for being a contestant

D. many countries chose some athletes to compete

查看答案和解析>>

科目：高中地理 來源： 題型：

【題目】如圖所示是一種利用電磁原理制作的充氣泵的結(jié)構(gòu)示意圖。其工作原理類似于打點(diǎn)計(jì)時(shí)器，當(dāng)電磁鐵通入電流時(shí)，可吸引或排斥上部的小磁鐵，從而帶動(dòng)彈性金屬片對(duì)橡皮碗下面的氣室施加力的作用，達(dá)到對(duì)外充氣的效果。請(qǐng)回答以下問題：

（1）當(dāng)電流從電磁鐵的接線柱a流入時(shí)，發(fā)現(xiàn)吸引小磁鐵向下運(yùn)動(dòng)，則電磁鐵的上端為________極，小磁鐵的下端為________極。

（2）你認(rèn)為這種充氣泵是利用直流電好，還是利用交流電好？答案：________

（3）纏繞電磁鐵用的鐵芯可分為硬磁性材料和軟磁性材料。硬磁性材料在磁場(chǎng)撤去后還會(huì)有很強(qiáng)的磁性，而軟磁性材料在磁場(chǎng)撤去后就沒有明顯的磁性了。你認(rèn)為這種鐵芯最好用________材料制作。

查看答案和解析>>

科目：高中地理 來源： 題型：

【題目】短文改錯(cuò)

假定英語課上老師要求同桌之間交換修改作文，請(qǐng)你修改你同桌寫的以下作文。文中共有10處語言錯(cuò)誤，每句中最多有兩處。錯(cuò)誤涉及一個(gè)單詞的增加、刪除或修改。

增加：在缺詞處加一個(gè)漏詞符號(hào)（∧），并在其下面寫出該加的詞。

刪除：把多余的詞用斜線（\）劃掉。

修改：在錯(cuò)的詞下劃一橫線，并在該詞下面寫出修改后的詞。

注意：

1. 每處錯(cuò)誤及其修改均僅限一詞；

2. 只允許修改10處，多者（從第11處起）不計(jì)分。

It was the International Women’s Day. Li Hua had a good idea and tells his father that he was going to do everything to celebrate it. He asked his father to help him. First they decided to do some housework, that was always done by his mother. Li Hua cleaned the house completely while his father did some shop. Then they made a good meal, cooking fish, pork, chicken, soup but some other delicious dishes. Li Hua laid the table and set a vase full with flowers in the middle of the table. After that they hid them behind the door and waited the mother in order to give her a surprise. When his mother came back and saw the delicious food, she felt happily.