极坐标法放样点位,适用于______,并且放样点位离控制点较近,又便于测量距离。其计算和操作都比较简单灵活。
A.平坦地带 B.丘陵地区C.多山地区 D.高原地带
参考答案:A
Hello. My name is Chen Lei. I study in Sunson Middle School-- a小题1:(美丽) school with more than 5000 students and小题2:(教师). My home is only two【小题3】(公里).So I walk there every day. It小题3:(通常) takes me about 20 minutes. I often小题4:(看) books and newspapers in the小题5:(图书馆) because it’s小题6:(安静) and I can get there小题7:(容易地).
I have a pen pal from小题8:(加拿大). There are four小题9:(儿童) in his family. His parents are小题10:(严格) with them. He 【小题12】(锻炼) every day. So he is healthy and never goes to小题11:(医院). He enjoys小题12:(爬) mountains and the 【小题15】(故事) telling is his favorite. Do you like him?
如图甲所示,质量为m的物体沿倾角为θ的固定粗糙斜面由静止开始向下运动,风对物体的作用力沿水平方向向右,其大小与风速v成正比,比例系数用k表示,物体加速度a与风速v的关系如图乙所示,求:
(1)物体与斜面间的动摩擦因数μ;
(2)比例系数k。