图3中各摆球可视为质点，各段绳长均为l，摆角均小于10°，(a)图在垂直纸面内摆动，(b)图中电梯匀加速上升，加速度为a，(c)图摆球带正电，磁场垂直纸面向外，(d)图摆球带正电，电场方向向下．以下说_刷题宝

题干

图3中各摆球可视为质点，各段绳长均为l，摆角均小于10°，(a)图在垂直纸面内摆动，(b)图中电梯匀加速上升，加速度为a，(c)图摆球带正电，磁场垂直纸面向外，(d)图摆球带正电，电场方向向下．以下说法正确的是（）

A：a图中摆球的周期最小

B：b和d图中摆球的周期不可能相等

C：c图中摆球的周期与未加磁场时是相同的

D：d图中摆球的周期是最大的

上一题下一题 0.0难度选择题更新时间:2020-01-30 06:11:52

答案(点此获取答案解析）

C

同类题1

目前，南宁市正在进行地铁建设，修建地铁广泛使用金属材料，下列不属于合金的是（）

同类题2

俗话说：半大小子，气死老子。许多家长抱怨说，孩子进入初中后特别不听话，叫他向东他向西，让他不干他非要干。孩子这种心理属于（）

同类题3

A: ____

B: I'm looking for a CD for my friend's birthday.

A: ____ This CD is very popular among young people now.

B: Let me see. It is rock music. I don't think she will like it.

A: ____

B: She likes music that is quiet and smooth.

A: Oh, I see. Please have a look at this CD. The music is soft and also popular.

B: That's great. I'd like to listen to the music. ____

A: OK. Wait a moment. I'm sorry this one is broken.

B: Do you have any more?

A: No, we don't. But we will have more in a few days. Please leave your phone number. ____

B: Thank you very much. My phone number is 819-9476.

A: You're welcome. See you.

B: See you.

A. How about this one?

B. What can I do for you?

C. Can you play it for me?

D. When we get more, we will call you.

E. What kind of music does she like?

同类题4

照样子，填上适当的词。

一____老鹰一____大山一____白云一____大树

同类题5

已知函数 $f (x) = \cos x, x \in (0, 2 π)$ 有两个不同的零点 $x_{1}, x_{2}$ ，且方程 $f (x) = m$ 有两个不同的实根 $x_{3}, x_{4}$ .若把这四个数按从小到大排列构成等差数列，则实数 $m$ 的值为

小学学科试题库

初中学科试题库

高中学科试题库