问题
选择题
— What beautiful clothes you are wearing! They must be expensive.
— No. They only ____ me fifty yuan. [ ]
A. cost
B. spent
C. paid for
D. took
答案
答案：A
搜题请搜索小程序“爱下问搜题”
— What beautiful clothes you are wearing! They must be expensive.
— No. They only ____ me fifty yuan. [ ]
A. cost
B. spent
C. paid for
D. took
答案：A
如图所示，物体从光滑斜面上的A点由静止开始下滑，经过B点后进入水平面，最后停在C点．现每隔0.2s通过传感器测量物体的运动速率v，下表给出了部分测量数据．设物体经过B点前后速率不变，重力加速度g取10m/s2．求：
| t（s） | 0.0 | 0.2 | 0.4 | 0.6 | … | 1.4 | 1.6 | … |
| v（m/s） | 0.0 | 0.0 | 1.0 | 2.0 | … | 1.1 | 0.7 | … |
（2）物体与水平面之间的动摩擦因数μ
（3）物体运动到B点时的速率VB．
