问题 不定项选择

如图所示,两个质量相等的物体A、B处在同一水平线上,当物体A被水平抛出的同时,物体B开始自由下落,图中曲线AC为物体A的运动轨迹,直线BD为物体B的运动轨迹,两轨迹相交于O点,空气阻力忽略不计,则

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A.两物体在O点时的速度相同

B.两物体在O点相遇

C.两物体在O点时的动能相等

D.两物体在O点时重力的功率相等

答案

BD

阅读理解

A thief entered the bedroom of the 30th President of the United States, who met him and helped him escape punishment.

The event happened in the early morning hours in one of the first days when Calvin Coolidge came into power, late in August, 1923. He and his family were living in the same third-floor suite(套房) at the Willard Hotel in Washington that had occupied several years before. The former President’s wife was still living in the White House.

Coolidge awoke to see a stranger go through his clothes, remove a wallet and a watch chain.

Coolidge spoke, “ I wish you wouldn’t take that.”

The thief, gaining his voice, said, “ Why?”

“ I don’t mean the watch and chain, only the charm(表坠). Take it near the window and read what is impressed on its back,” the president said.

The thief read, “ Presented to Calvin Coolidge.”

“ Are you President Coolidge?” he asked.

The president answered, “ Yes, and the House of Representatives(众议院)gave me the watch charm. I’m fond of it. It would do you no good. You want money. Let’s talk this over.”

Holding up the wallet, the young man said in a low voice, “ I’ll take this and leave everything else.”

Coolidge, knowing there was 80 dollars in it, persuaded the young man to sit down and talk. He told the President he and his college roommate had overspent during their holiday and did not have enough money to pay their hotel bill.

Coolidge added up the roommate and two rail tickets back to the college. Then he counted out 32 dollars and said it was a loan(借款).

He then told the young man, “ There is a guard in the corridor.” The young man nodded and left through the same window as he had entered.

单项选择题