a 4 foot by 8 foot panel, the top of wich is located 18 foot below the water line on a dam wall is subject to how much forec? ( assume the panel is oriented with the long side horizontal)
It depends on what you call the top of the plywood.
(Mass of water + mass of dam + mass of land that are all under 18 feet) x 9.81 m/s^2.... Not enough info really dude.
To determine the force exerted on the panel, you need to calculate the hydrostatic pressure acting on it. The hydrostatic pressure depends on the depth of the panel below the water line.
Here's how you can calculate the force exerted on the panel:
1. Determine the depth of the panel below the water line:
The top of the panel is located 18 feet below the water line on the dam wall.
2. Calculate the depth of the water above the panel:
The height of the panel is 4 feet, so the water level above the panel would be 4 feet + 18 feet = 22 feet.
3. Convert the depth from feet to inches:
Convert the depth of water above the panel from feet to inches by multiplying by 12, since there are 12 inches in a foot.
22 feet * 12 inches/foot = 264 inches.
4. Calculate the hydrostatic pressure:
The hydrostatic pressure exerted by a fluid depends on its density and the depth of the fluid column.
The density of water is approximately 62.4 pounds per cubic foot.
Hydrostatic pressure (P) = density (ρ) * acceleration due to gravity (g) * depth (h).
P = ρ * g * h.
The acceleration due to gravity (g) is approximately 32.2 feet per second squared.
P = 62.4 pounds/cubic foot * 32.2 feet/second² * 264 inches / 12 inches/foot.
5. Convert the pressure from pounds per square foot to pounds:
The pressure calculated above is in pounds per square foot. To get the force, you need to convert it to pounds by multiplying by the area.
The area of the panel is the length multiplied by the width.
Area = 4 feet * 8 feet = 32 square feet.
Force = Pressure * Area.
Finally, by multiplying the pressure by the area, you will obtain the force exerted on the panel.
Please note that the above calculation assumes that the water above the panel is static and not flowing. If there is flow, additional considerations may need to be taken into account.