问题 选择题

关于物体的动量、冲量、动量的变化量,下列说法正确的是(  )

A.物体受的力越大,力的冲量就越大

B.冲量与动量的单位在国际单位制下是相同的,所以冲量就是动量

C.某个物体的动量变化越快 ,它受到的合外力一定越大

D.某个物体的动能变化,则它的动量一定变化

答案

CD

题目分析:动量P=mv,冲量I=Ft,动量的变化等于冲量。根据相应公式判断可知,A错误。冲量等于动量该变量,所以B错误。某个物体的动量变化量为冲量,因此某个物体的动量变化越快 ,它受到的合外力一定越大,C对。根据可知,某个物体的动能变化,则它的动量一定变化,D对

点评:本题考查了动量、冲量、动量的变化量之间的关系,需要了解这些物理量的公式才能区分这些物理量。

阅读理解

Giving Back

Fair Way

The Westborough High School golf team had taken the official photos with the state prize. The other teams, disappointed, were on the bus heading home. And then Westborough instructor Greg Rota noticed something wrong x>n one of the score cards. A 9 had been recorded as a 7. They were not the state prize winner; Wobum High had won. "No one would have known," said Wobum's instruc­tor, Bob Doran. For Rota, it wasn't a difficult decision: "The prize wasn't ours to take."

Coin Stars

"College students are lazy, but they also want to help," says University of Pennsylvania graduate Dana Hork. So she made it easy, placing cups in rooms where students could leave their spare coins, and handing out cups to first-year students to keep in their rooms. Her " Change for Change" effort has collected $40,000 for charities 慈善机构), which were decided upon by students.

Never Forgotten

A school in Massachusetts received a $ 9.5 million check from Jacques LeBermuth. But it took offi­cials several days of digging to discover his connection to the school. Records showed the LeBermuth came from Belgium and studied in the school in the 1920s. When his family fell on hard times, he was offered free room and board. LeBermuth became a trader, owned shares of AT&T and lived off the earnings until he died, at age 89.

60. What did Greg Rota probably do in the end?

A. Took photos of Doran.

B. Had a meeting with Doran.

C. Returned the prize to the organizer.

D. Apologized to Wobum High School.

61. Greg Rota's decision shows that he was _______.

A. honest              B. polite               C. careful              D. friendly

62. The underlined word "Change" in the second paragraph means _______.

A. Idea           B. Decision      C. Cups               D. Coins

63. What did the school officials do after receiving the check from Mr. LeBermuth?

A. They tried to find out why he gave them the money.

B. They went to Belgium to pay their respects to him.

C. They dug out the records that were buried underground.

D. They decided to offer their students free room and board.

64. Jacques LeBermuth gave the money to the school because _______.

A. the school asked for it                

B. he had no need for that much money

C. the school had helped him in the past  

D. he wanted to be remembered by the students

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