Fluid Pressure and Fluid Force Lesson 7.7

Fluid Pressure Definition: The pressure on an object at depth h is Where w is the weight-density of the liquid per unit of volume Some example densities water 62.4 lbs/ft3 mercury 849 lbs/ft3

Fluid Pressure Pascal's Principle: pressure exerted by a fluid at depth h is transmitted equally in all directions Fluid pressure given in terms of force per unit area

Fluid Force on Submerged Object Consider a rectangular metal sheet measuring 2 x 4 feet that is submerged in 7 feet of water Remember so P = 62.4 x 7 = 436.8 And F = P x A so F = 436.8 x 2 x 4 = 3494.4 lbs

Fluid Pressure Consider the force of fluid against the side surface of the container Pressure at a point Density x g x depth Force for a horizontal slice Density x g x depth x Area Total force

Fluid Pressure The tank has cross section of a trapazoid Filled to 2.5 ft with water Water is 62.4 lbs/ft3 Function of edge Length of strip Depth of strip Integral (-4,2.5) (4,2.5) 2.5 - y (-2,0) (2,0) y = 1.25x – 2.5 x = 0.8y + 2 2 (0.8y + 2) 2.5 - y

Assignment Lesson 7.7 Page 511 Exercises 1-25 odd