自由下落的物体，在任何相邻的1s内下落的距离之差△h和平均速度之差△
在数值上分别等于（ ）. v
A．
，2gg 2
B．
，g 2 g 4
C．g，g
D．g，2g
在第1个单位时间T=1秒内，下落距离是 h1=
gT2=1 2
g×12=1 2
；g 2
在第1个单位时间内的平均速度：
=. V1
=h1 T
=g 2 1 g 2
在第2个单位时间T=1秒内，下落距离是 h2
则有：h1+h2=
g(2T)2=2g1 2
得：h2=2g-
=g 2 3g 2
在第2个单位时间内的平均速度：
=. v2
=h2 T
=3g 2 1 3g 2
所以：△h=h2-h1=
-3g 2
=gg 2
△
=. v
-. v2
=. v1
-3g 2
=gg 2
故选：C
The concept of solitude(独处) in the digital world is almost nonexistent.In the world of digital technology，email，social networking and online video games，information is meant to be ___.Solitude can be hard to discover____it has been given up.In this respect，new technologies have___our culture. The desire to be connected has brought solitude to a(n)____as we’ve known it.People have become so____in the world of networks and connections that one can often be contacted____they’d rather not be.Today we can talk，text，email，chat and blog(写博客)，not only from our____，but from our mobile phones as well. Most developed nations have become ____on digital technology simply because they’ve grown accustomed to it，and at this point not____it would make them an outsider.____，many jobs and careers require people to be____.From this point of view，technology has changed the culture of work.Being reachable might feel like a___to those who may not want to be able to be contacted at all times. I suppose the positive side is that solitude is still possible for anyone who____wants it.Computers can be shut____and mobile phones can be turned off.The ability to be “connected” and “on” has many____，as well as disadvantages.Travelers have ended up____on mountains，and mobile phones have saved countless lives.They can also make people feel ____and forced to answer unwanted calls or____to unwanted texts. Attitudes towards our connectedness as a society____across generations.Some find today’s technology a gift.Others consider it a curse.Regardless of anyone’s view on the subject，it’s hard to imagine what life would be like____daily advancements in technology.(2012·江苏)
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