问题 多选题

对于做匀速圆周运动的物体,下列说法正确的是(  )

A.相等的时间里发生的位移相等

B.相等的时间里转过的角度相等

C.向心加速度的方向始终与速度方向垂直

D.所受合外力的方向可能不指向圆心

答案

A、相等时间里位移的大小相等,方向不同,故A错误

B、角速度为标量,相等的时间里转过的角度相等,故B正确

C、向心加速度的方向指向圆心,始终与速度方向垂直,故C正确

D、由于是匀速圆周运动,合外力的方向一定不指向圆心,故D错误

故选BC

阅读理解

Once there was a huge apple tree. A little boy loved to come and play around it every day. He loved the tree and the tree loved to play with him.

Time went by…the little boy had grown up and he no longer played around the tree every day. One day, the boy came back to the tree and he looked sad. “Come and play with me,” the tree asked the boy. “I’m no longer a kid. I wouldn’t play around the tree any more.” the boy replied. “I want toys. I need money to buy them.” “Sorry, I don’t have money. But you can pick all my apples and sell them. So, you will have money.” The boy picked all the apples on the tree and left happily. The boy never came back after he picked the apples.

One day, the boy returned and the tree was so excited, “Come and play with me,” the tree said. “I don’t have time to play. I have to work for my family. We need a house for shelter. Can you help?” “Sorry, I don’t have a house. But you can cut off my branches to build your house.” So the boy cut all the branches off the tree and left happily. The tree was glad to see him happy but the boy never came back since then. The tree was again lonely and sad.

One hot summer day, the boy returned and the tree was pleased. “Come and play with me!” the tree said. “I am sad and getting old. I want to go sailing to relax myself. Can you give me a boat?” “Use my trunk to build your boat. You can sail far away and be happy.” So the boy cut the tree trunk to make a boat. He went sailing and never showed up for a long time.

Finally, the boy returned after he left for so many years. “Sorry, my boy. But I don’t have anything for you any more. The only thing left is my dying root,” the tree said with tears ①.

“Good! Old tree root is the best place to lean on and rest. Come and sit down with me and rest.” The boy sat down and the tree was glad and smiled with tears ② …

小题1:----Why did the boy pick all the apples on the tree?

----Because __________.

A.he wanted to eat them

B.he needed money to buy toys

C.he liked the tree without apples

D.he wanted to share them with friends小题2:----When did the boy come back to the apple tree?

----He came back _________.

A.whenever he was happy

B.if he missed the apple tree

C.when he was in times of difficulty

D.as soon as he was free小题3:----What did the boy want at last?

----He wanted ___________.

A.to have a house to live in

B.nothing except a place to rest

C.the root of the apple tree

D.anything that the apple tree had小题4:----What can we learn from the story?

----We should _________.

A.plant more apple trees

B.learn from the boy

C.always stay at home

D.be thankful to our parents小题5:According to the passage, which of the following statements is NOT true?

A.The phrase “with tears ①” means that the apple tree was sad because the boy asked for too much.

B.The phrase “with tears ②” means that the apple tree was still happy because she could help the boy for the last time.

C.Each time the boy asked the apple tree for help, the tree tried her best to satisfy him.

D.After reading the passage, we can easily think of the old Chinese saying “Parents’ love is universal!”

单项选择题