问题 多选题

以速度v0水平抛出一小球后,不计空气阻力,某时刻小球的水平分位移是竖直分位移的两倍,以下判断正确的是(  )

A.此时小球的竖直分速度等于水平分速度大小

B.此时小球速度的方向与位移的方向相同

C.从抛出到此时,小球运动的时间为

2v0
g

D.此时小球速度的方向与水平方向成45°

答案

由题意可知:v0t=2×

1
2
gt2

解得:t=

v0
g
;故C错误;

竖直分速度vy=gt=v0;故A正确;

小球的速度方向与水平方向成45°角;故D正确;

而位移的方向与水平方向间夹角的正切值为

1
2
,故速度方向和位移方向不相同,故B错误;

故选AD.

阅读理解

阅读短文,选择正确答案。

    Today is Saturday, Tom's wife is cleaning the house. 

    "Look at all these umbrellas." Tom's wife says to him. "There are eight and they are all broken (坏的)."

    "I want to take them all to the umbrella shop. Let the shop keeper — Mr Smith mend them." Tom says.

    Tom takes them to the shop. Mr Smith asks him to get them home on Sunday. Tom goes home from the

shop by bus. He sits beside an old woman. She has an umbrella on the floor near her.

    On the bus, Tom takes the old woman's umbrella by mistake. 

    "Hey!" The woman says. "That's mine." 

    "I'm so sorry." Tom says and gives the umbrella to the old woman.

    On Sunday, he gets the umbrellas from the umbrella shop and gets on the bus. He sits down, a woman says

to him, "You take so many umbrellas. You certainly have a successful (成功的) day!" She is the old woman

Tom met on Saturday.

1. Tom's wife finds the broken umbrellas _________. [ ]

A. in a shop

B. in their house

C. on the bus

D. in the street

2. Tom takes the umbrellas to a shop _________. [ ]

A. to sell

B. to mend

C. to throw away

D. to give them to others

3. On the bus, Tom _________. [ ]

A. takes a woman's umbrella.

B. finds his umbrella.

C. buys an umbrella

D. gives his umbrella to an old woman.

4. Who can mend the umbrella? [ ]

A. Tom.

B. Tom's wife.

C. The old woman.

D. Mr Smith.

5. What does the old woman think of Tom? [ ]

A. a shop keeper.

B. an umbrella seller.

C. a thief.

D. a mender.

单项选择题