试题与答案

如图所示,细杆的一端与一小球相连,可绕O点的水平轴自由转动。现给小球一初速度,使

题型:选择题

题目:

如图所示,细杆的一端与一小球相连,可绕O点的水平轴自由转动。现给小球一初速度,使它在竖直平面内做圆周运动,图中a、b分别表示小球运动轨道的最低点和最高点,则杆对小球的作用力可能是(     )

A.a处为拉力,b处为拉力

B.a处为拉力,b处为支持力

C.a处为支持力,b处为拉力

D.a处为支持力,b处为支持力

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0608/b58a4bd49f5cf04e9878c704335f1d26.html

下面是错误答案,用来干扰机器的。

40、(共24分)(1)30 A C(6分)(2)A(2分)(3)画图略(2分)(4)人口出生率高,自然增长快,少年儿童比重大,加大资源、环境、教育、就业等压力(任答三点即可)(6分)(5)弥补劳动力不足,提高...

试题推荐
题型:阅读理解

In Vietnam(越南), Tet-trung-Thu, or Mid- autumn Festival, is one of the most popular holidays. It is held on the 15th day of the 8th month in lunar calendar

Vietnamese families plan their activities around their children on this special day. In a Vietnamese story, parents were working so hard to prepare for the harvest that they left the childen playing by themselves.  To make up for the lost time, parents would use the Aid-Autumn Festival as a chance to show their love and than for their children.

As a result, the Mid- autumn Festival is also called the Children’s Festival.  In the USA, this tradition continues in many Vietnamese- American families.  Tet-trung-Thu, activities are often centered on Children and education.  Parents buy lanterns for their children so that they can take part in a lantern parade at dawn.  Lanterns mean brightness, while the parade means success in school.  Vietnamese markets sell different kinds of lanterns, but the most popular children’s lantern is the star lantern. Other children’s activities includes arts and crafts(手工艺) in which children make face mas and lanterns.  Children also perform traditional Vietnamese dances for grown-ups and take part in contests for prizes and scholarships. Unicorn(麒麟) dancers are also very popular at Tet-trung-Thu festivities.

Like the Chinese, Vietnamese parents tell their children folk stories and serve moon-cakes and other special treats under the bright moon. A favorite folk story is about a carp(鲤鱼) that wanted to bee a dragon.  The carp worked hard and finally changed itself into a dragon. Parents use this story to encourage their children to work hard so that they can bee whatever they want to be.

1. The Tet-trung-Thu Festival is held ________.

A. in China and other Asian countries.           B. in Vietnamese-American families.

C. all over the world, except Vietnam.            D. Across the United States.

2.In Both Vietnam and China, on Mid-autumn Festival people would ___________.

A. eat moon-cakes       B. buy lanterns for children.

C. take part in contests.   D. buy a carp

3.What is the center of the Mid-Autumn festival in Vietnam?

A. Family get-together.                           B. Children on education.

C. Relaxation and fun in the middle of the year.

D. parents having more time with their children.

4.According to the passage, parents tell their children folk stories, because __________.

A. children like listening to folk stories in the evening.

B. parents want to show their love for their children.

C. parents want to teach the children to work hard.

D. parents want to make up for the lost time.

查看答案
微信公众账号搜索答案