A triangular plate with height 6 ft and a base of 8 ft is submerged vertically in water so that the top is 3 ft below the surface. How do you express the hydrostatic force against one side of the plate as an integral and evaluate it?

A triangular plate with height 6 ft and a base of 8 ft is submerged vertically in water so that the top is 3 ft below the surface. Express the hydrostatic force against one side of the plate as an integral and evaluate it. (Recall that the weight density of water is 62.5 lb/ft^3.ft3.)

1 Answer

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Explanation:

It's int_3^993 4/343 deltaδ (9 - x)x dx. Solving it gives us:

= 4/343 int_5^995 deltaδ (9 - x)x dx

= 4/343 deltaδ int_3^993 9x - x^2x2 dx

= 4/343 deltaδ [9/292 x^2x2 - 1/313 x^3x3 ]_3^9]93 dx

= 4/343 deltaδ [9/292 9^292 - 1/313 9^393 - (9/292 3^232 - 1/313 3^333)]

= 4/343 deltaδ [9/292 8181 - 1/313 729729 - (9/292 99 - 1/313 2727)]

= 4/343 deltaδ [729/27292 - 729/37293 - (81/2812 - 27/3273)]

= 4/343 deltaδ [729/27292 - 729/37293 - 81/2812 + 27/3273]

= 4/343 deltaδ [729/27292 - 81/2812 - 729/37293 + 27/3273

= 4/343 deltaδ [648/26482 - 702/37023]

= 4/343 deltaδ [648/26482 - 702/37023]

= 4/343 deltaδ [324 - 234]

= 4/343 deltaδ [90]

= 360/33603 deltaδ

= 120 deltaδ

Note that deltaδ is the weight of density of water. Now we must use deltaδ = 62.5

= 120(62.5)

= 7500