问题 多选题

如图所示,在特制的弹簧秤下挂一吊篮A,吊篮内挂一重物B,一人站在吊篮中,当此人用100N的竖直向下的力拉重物时,下列说法中正确的是(  )

A.弹簧秤示数不变

B.人对底板的压力减小100N

C.B的合力增大100N

D.A的合力不变

答案

A、以吊篮A、重物B和人整体为研究对象,由平衡条件得知:弹簧秤的拉力等于总重力,保持不变,则弹簧秤示数不变.故A正确.

B、以人为研究对象,分析受力情况:重力G、底板的支持力N和拉力F,由平衡条件得,N=G-F,而原来底板对人的支持力等于G,则底板对人支持力减小F=100N,由牛顿第三定律得知,人对底板的压力减小100N.故B正确.

C、B处于静止状态,合力为零,保持不变.故C错误.

D、吊篮A处于静止状态,合力为零,保持不变.故D正确.

故选ABD

问答题 简答题
阅读理解

If you like bicycling as much as you like playing ball and can’t seem to decide between the two sports, you may want to consider cycle ball—a fun sport that adopts the key attributes from both activities and transforms it into a totally new game..

Also known as red ball, the game was invented in 1893 by German laborers who wished to play polo(马球), but could not afford horses. While the sport has not caught on in North America, it is very fashionable in Europe and even Japan.

Played in an indoor court, cycle ball is similar to soccer in many ways—the aim is to score as many goals as possible, and only the goalkeeper is allowed to touch the ball.

The one big difference? Use of legs is forbidden. Instead, players have to guide the ball across the court, using the front wheels of their bicycles or with their heads. In fact, if a player even touches the floor with his feet during the 14-minute game, it is considered a foul(犯规) and the opposing team gets a free kick.

While the game was initially(最初) played with normal bikes, things are a little different now. The seats of these specialized bikes are positioned over the back tire and they sport a single fixed gear, making it easier for the rider to control the constant back and forth movement required for the game. The handlebars(车把) also point straight up so that the competitors can sit upright while playing and they are about twice the weight of normal bikes, which helps with the stability.

While cycle ball may sound a little strange, it is a fast-paced sport that requires much training, skill, and, is also really fun to watch.

小题1:What does the passage mainly talk about?

A.The origin and development of soccer

B.The differences between cycle ball and soccer.

C.The most popular sports game in the world.

D.A new and fun sports game—cycle ball小题2:What does the underlined phrase “caught on” in Paragraph 2 probably mean?

A.turned up

B.hung up

C.come about

D.become popular小题3:What can we know about cycle ball?

A.It is a fast-paced game played in an indoor court

B.It was invented in 1893 by poor British people.

C.It is another name of soccer played by many people.

D.It is a strange game played with normal bikes.小题4:It can be known from the passage that __________.

A.every player who is playing cycle ball is allowed to touch the ball.

B.the aim of playing cycle ball is to score as many goals as possible.

C.if a player touches the floor with his feet, the opposing team will win

D.heads are not allowed to be used to guide the ball across the court.小题5:Which of the following is TRUE according to the text?

A.Cycle ball is popular both in Japan and other Asian countries.

B.The cycle ball game is popular all over the world.

C.A cycle ball game takes 14 minutes.

D.Cycle ball has to be played with heads, legs or the front wheels.