14、圖 14 中，水穩定流通過此延著水平面改變面積的管路，中心線的速度為： V = 100(1+x)i m/s. 阻力被忽略不計，計算所需要的壓力差使得水穩定流通

10、 In Figure 10, a horizontal force of 500 N acts on a block of weight 1.5 kN placed on an inclined plane. The coefficients of friction between the block and the plane are μs =0.25 andμk = 0.20 . What is the actual frictional force? (A) 200N (B) 500 N (C) 300 N (D) 450 N。