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【简答题】
（14分）如图甲所示，“
”形木块放在光滑水平地面上，木块水平表面AB粗糙，光滑表面BC与水平面夹角为θ＝37°。木块右侧与竖直墙壁之间连接着一个力传感器，当力传感器受压时，其示数为正值；当力传感器被拉时，其示数为负值。一个可视为质点的滑块从C点由静止开始下滑，运动过程中，传感器记录到的力和时间的关系如图乙所示。已知sin37°＝0.6，cos37°＝0.8，g取10m/s 2，求：
(1)斜面BC的长度； (2)滑块的质量； (3)运动过程中滑块克服摩擦力做的功。
参考答案：
参考解析：
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举一反三
【单选题】In the wake of 11 September, Visionics, a leading manufacturer, issued a fact sheet explaining how its technology could enhance airport security. They called it "protecting civilization from the faces...
A.
any way, the face-recognition technology is good enough to frighten the terrorists
B.
the industry will have to recognize the real situation and work hard to improve the technology
C.
all the claims are premature
D.
we must not expect too much
【单选题】Passage 4 In the wake of 11 September, Visionics, a leading manufacturer, issued a fact sheet explaining how its technology could enhance airport security. They called it "protecting civ...
A.
Too many false alarms were raised.
B.
Everyone should look straight at the camera.
C.
Only 90% of suspects at an airport were found.
D.
Everyone should not disguise himself.