题干

将一根金属杆在竖直向下的匀强磁场中以垂直磁场方向的初速度υ水平抛出,若金属杆在运动过程中始终保持水平,那么金属杆的感应电动势E的大小将( )

A:随杆的速度的增大而增大

B:保持不变

C:随杆的速度方向与磁场方向夹角的减小而减小

D:因为速度的大小与方向同时变化,因此无法判断E的大小。

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答案(点此获取答案解析)

B

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阅读理解

         Who do you think was the most important woman of the past 100 years?

         Jane Addams(1860—1935)

         Addams helped the poor and worked for peace. She created shelters, education opportunities and services for people in need. In 1931, Addams became the first American woman to win the Nobel Peace Prize.

         Rachel Carson(1907—1964)

         Rachel Carson was born in the rural river town of Springdale, Pennsylvania in America. The popular 1962 book SilentSpring by Rachel Carson made people realize the dangers and the harmful effects(影响) of pollution on humans and on the world's lakes and oceans.

         Angela Merkel(1954—)

         In 2005, Germans chose Angela Merkel as their first woman head of the country. She had been a scientist in the past. As Germany's leader, she has had an effect on the whole world.

         Sandra Day O'Connor(1930—)

         When Sandra Day O'Connor finished her class at Stanford Law School in 1952, she could not find work because she was a woman. However, she became the first woman to join the US Supreme Court(最高法院) in 1981 after years of hard work.

         Margaret Thatcher(1925—2013)

         In 1979, Margaret Thatcher became Britain's first woman Prime Minister(首相). She served until 1990, which made her the first British leader to serve three terms in a row. Because of her high standards and strong will, people called her Britain's “Iron Lady”.

          Marie Curie(1867—1934)

         Polish­born scientist Marie Curie discovered that some types of metal give off energy called radiation(辐射能). Her research led to new medical treatments and arms. She received the Nobel Prize in Physics in 1903 and in Chemistry in 1911.