如图所示，从倾角为θ的斜面上的M点水平抛出一个小球，小球的初速度为υ0，最后小球落在斜面上的N点，已知重力加速度为g，下列判断中正确的是（ ）
A．可求出M、N之间的距离
B．可求出小球运动的时间
C．不可以求出小球什么时刻与斜面间的距离最大
D．可求出小球落到N点时的速度大小和方向
B、由题意可知，小球飞过的位移与水平方向成θ角；将位移分别沿水平方向和竖直方向分解，由几何关系可知：
tanθ=
gt21 2 v0t
解得：t=
，故平抛运动的时间可求；故B正确；2v0tanθ g
A、由时间则可求得小球经过的竖直高度和水平位移；则由几何关系可知l=
，故距离可求出，故A正确；x2+y2
C、将初速度沿斜面和垂直于斜面进行分解，同时将加速度也同方向分解；当垂直于斜面的速度为零时，小球距离斜面最远，由于初速度和加速度已知，故时间可求；故C错 误；
D、由vy=gt，可求得竖直分速度，由速度的合成与分解可求得最后末速度的大小和方向，故D正确；
故选ABD．
请认真阅读下列短文，并在文章后表格中的空格里填入一个最恰当的单词。每空一词。 In the United States, engineering is a profession that has been dominated historically by men． Even today, it’s still true that few women become civil or chemical or mechanical engineers, but that’s something www．EngineerGirl．org aims to change． Young women who visit the web site can find out about a great career choice they might not have considered． “Women are very much underrepresented in engineering and in engineering education programs and then of course, down the road, in the engineering workforce． So only about 20 percent of engineering undergraduate degrees go to women, and then only about nine percent of working engineers are women．” Mary Mattis in the National Academy of Engineering, says the EngineerGirl website aims to reach young women around ages 11 through 14, when they are just getting old enough to start thinking about their futures． “We know from the research that middle-school girls are at a critical point in their lives, and that it’s a time when we need to reach them, both with an understanding, increasing their awareness of interesting fields in engineering, what a wonderful productive and exciting career you can have as an engineer． But we also need to reach them at that time because you have to take certain courses, and you can’t start thinking about taking those courses when you’re a junior in high school．” Engineering is a demanding course of study ---there is a lot of science and mathematics, for many girls and even boys, that can be challenging． But Ms． Mattis says that the EngineerGirl website stresses that engineering can also be fun and exciting． “It’s about designing things． It’s about changing the world for people． It’s about making a difference． And, in addition, you can make a good living, you can be independent economically by becoming an engineer． All of those things are messages that girls need to get．” While most engineers go into traditional fields such as mechanical and electrical engineering, the EngineerGirl site also highlights unusual engineering careers in fields such as sports engineering and --- believe it or not --- chocolate engineering． “There’s a section called ‘why be an engineer,’ and that talks about the many opportunities and increasingly different opportunities like with bio-engineering and environmental engineering, some fields that might appeal to girls who want to make a difference or have a meaning for their careers beyond earning an income．” Even if you are not a girl in the target age group, there’s a lot of interesting information on the site, including biographies of some notable women engineers．
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