【单选题】已知直线上两点的高差是3米,两点间的水平投影长度是9米,该直线的平距为多少?The height difference between two points on a straight line is 3m, and the length of the horizontal projection is 9m, what is the horizontal distance of the line?
【简答题】An object was a mass of 10.0 kg is at rest at the top of a frictionless inclined plane of length 8.00 m and an angle of inclination 30.0°with the horizontal. The object is released from this position ...