问题
单项选择题
一个物体从高h处自由落下，其时间达到落地时间一半时，下落的高度为（）
A.
h
B.
h
C.
h
D.
h
答案
参考答案：B
解析：
设石块落地时的速度大小为v，由：v2-v02=2gx；得：
v2-0=2gh…①；
②；
由①②解得：h′=
，故选B
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一个物体从高h处自由落下，其时间达到落地时间一半时，下落的高度为（）
A.h
B.h
C.h
D. h
参考答案：B
解析：
设石块落地时的速度大小为v，由：v2-v02=2gx；得：
v2-0=2gh…①；②；
由①②解得：h′=，故选B
| 阅读理解。 | ||
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| 1.It's Friday afternoon, you can go to ______. | ||
[ ] | ||
| A.visit the museum B.play soccer C.play basketball D.read children's stories | ||
| 2.If children want to watch new films, they should go to ______. | ||
[ ] | ||
| A.16 yangtze Road B.89 Noth Main Street C.106Green Street D.99 Brick Road | ||
| 3.If you dial (拨号) 66387901, you can ______. | ||
[ ] | ||
| A. ask for some hotel information B.do some shopping C.have a good story time D.order fast food in a restaurant | ||
| 4.Lily's father is ill. She should dial ______. | ||
[ ] | ||
| A.800-120-9847 B.79210583 C.68787451 D.96725643 | ||
| 5.You can not get any information about ______ from the two notices. | ||
[ ] | ||
| A.looking for a hotel B.doing eye exercises C.eating fast food D.taking a taxi |