368 



HYDRAULICS AND ITS APPLICATIONS 



(2) Oblique Impact on a Stationary Plane Surface (Fig. 164). 



Assuming the jet to be of the same width as the plane and to be pre- 

 vented from spreading sideways by flanges, part of the stream will escape 

 from each end of the plane. The sectional area of each of these streams 

 can be calculated by expressing the fact that the change of momentum 

 parallel to the plate is unchanged by impact if friction be neglected. 



FIG. 165. 



Suppose the jet of unit width and of area t, the thickness of the discharge 

 streams being t\ and 2 . 



Let be the (acute) angle between the direction of the jet and the 

 plane, v the velocity of the jet. 



Then initial momentum parallel to plane = - - cos * 



W v 2 

 and final momentum parallel to plane ; 



But 



Also 



. *. t cos = t% ti 

 t =: tz h 



9 



i cos e . 



I + cos 0* **" * 2 



