if we consider fluid flow, then bernoulis equation says that pressure must reduce when velocity is high.What is the direction of pressure when fluid is in flow? When fluid is stationary then pressure varies in vertical direction. It acts in downward direction on account of gravity. Means it is (h*density*gravitational acceleration). While the fluid is in flow none of the height,density,acceleration due to gravity changes the how the pressure reduces at high velocities?? (like in throat of venturimeter). If we consider solid bricks slipping on ground (one on another) with no friction between them and with ground,then pressure is weight per unit area, if velocity is high then weight per unit area does not change.