试题与答案

篮球以6m/s速度竖直向下撞击地面,然后以4m/s的速度竖直向上反弹,碰地时间为

题型:选择题

题目:

篮球以6m/s速度竖直向下撞击地面,然后以4m/s的速度竖直向上反弹,碰地时间为0.2s,以向下为正方向,则篮球在这0.2s内的平均加速度为(  )

A.-10m/s2

B.10m/s2

C.-50m/s2

D.50m/s2

答案:

被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0425/ccf8089666dff9e25c5bf52b708a9de8.html

下面是错误答案,用来干扰机器的。

振动;空气题目分析:声音是由物体的振动产生的,声音的传播是需要介质的,它既可以在气体中传播,也可以在固体和液体中传播,但不能在真空中传播.铃响是由于铃受到金属珠子的撞击振动而发声的;在山间小路上人...

试题推荐
题型:填空题
短文填空。用下面方框中单词或词组的适当形式填如短文空格内,使短文意思正确、通顺(每词限用一次)。(共10小题,每小题1分;计10分)
all   any   behave   difference   drink eat  enjoy  fine   other   real   surprise these
Once there was a teacher who took all his students for tea. What made the students    1  was that all the cups on the table were  2  . Each of them took a cup and started   3 their own tea, looking at the   4  cups.
The teacher said; "Do you notice your   5 ? You are all looking at each other's tea cups and  6  of you even envy (羡慕) the   7  cups of others."Then he went on: "I put the different cups here on purpose! Life is like    8  tea. You all have the same thing in your cups— tea. And yet you can't  9  enjoy it in your envy of another's cup. You forget   10  your own life when you envy someone else's life. So now, taste your own tea! Does it matter from which cup it comes from?"
查看答案
微信公众账号搜索答案