题干

如图所示,在点电荷Q形成的电场中,a、b两点在同一等势面上,c、d两点在另外同一等势面上,甲、乙两带电粒子只在电场力作用下的运动轨迹分别为acb和adb曲线.若两粒子通过a点时具有相同的动能,则(   )

A:甲、乙两粒子带异号电荷

B:两粒子经过b 点时的动能相同

C:甲粒子经过c点时与乙粒子经过d点时的动能相同

D:若取无穷远处为零电势,则甲粒子在c点的电势能小于乙粒子在d点时的电势能

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答案(点此获取答案解析)

A,B,D

同类题5

阅读理解

C

    Yangzhou paper-cutting, with a history of 2,000 years, can be dated back to the Sui Dynasty, making Yangzhou one of the places where paper-cutting first became popular.

    In the Sui Dynasty, the people of Yangzhou would cut colourful paper or silks and satins(缎子) to celebrate festivals. It is said that Emperor Yang came to Yangzhou three times. In winter, the flowers and trees in the garden become dry and weak. The Emperor ordered the girl servants to cut fine silks and satins into flowers and leaves and use them to decorate the trees and lakes, copying nicely the looks of spring and summer. Since then, “colorful brocade cutting” (织锦缎) has become a popular art in Yangzhou.

    In the Tang Dynasty, the paper-cutting industry was highly developed and a large amount of high-quality paper was made as presents to the Court(宫廷).

    In the Qing Dynasty, because of the economic development, the people of Yangzhou became interested in wearing fine clothing, especially embroidered clothing(刺绣). The embroidered designs was based on paper-cuts. The most well-known of them was Bao Jun, a paper-cutting master. He won a high reputation(名声) as Magic Scissors(剪刀) for his wonderful cutting skills.

    After the People's Republic of China was started, the Chinese government accepted the importance of paper-cutting like many other arts and skills. In 2007, China Paper-cuts Museum opened to the public in the back garden of the Wangs' Residence(住所), Yangzhou, greatly helping the development of Yangzhou paper-cutting.