- #1

Keldroc

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Hey guys, I have a couple of problems about hydrostatic force and center of a mass that I was hoping someone could help me out with.

Sketch the region bounded by the curves y=2x^3, x+y=3 and y=0. Find the coordinates of the centroid.

Sorry I don't know how to make equations appear on here so I'll just type them out:

M=int f(x)-g(x)dx from a to b

x bar= 1/M * int x[f(x)-g(x)]dx from a to b

y bar= 1/M * int (1/2)[f(x)^2-g(x)^2]dx from a to b

I used y=3-x for f(x) and y=2x^3 for g(x) and plugged them into the equations, used a=0 and b=3 and I got the wrong answer so I'm not sure what to do now.

Find the following questions at the depth of 25m. The gravitational acceleration is g=9.8m/s^2 and the density of water is =1000kg/m^3:

Find the hydrostatic force on a square steel plate with sides 3m placed vertically.

Pressure=[tex]\rho[/tex]gd

F=Pressure * Area

For pressure I did P=(1000kg/m^3)(9.8m/s^2)(25m)= 245000

Then, did Force=(245000 Pa)(3m * 3m)=2205000 N and it was the wrong answer.

**Center of mass**## Homework Statement

Sketch the region bounded by the curves y=2x^3, x+y=3 and y=0. Find the coordinates of the centroid.

## Homework Equations

Sorry I don't know how to make equations appear on here so I'll just type them out:

M=int f(x)-g(x)dx from a to b

x bar= 1/M * int x[f(x)-g(x)]dx from a to b

y bar= 1/M * int (1/2)[f(x)^2-g(x)^2]dx from a to b

## The Attempt at a Solution

I used y=3-x for f(x) and y=2x^3 for g(x) and plugged them into the equations, used a=0 and b=3 and I got the wrong answer so I'm not sure what to do now.

**Hydrostatic Force**## Homework Statement

Find the following questions at the depth of 25m. The gravitational acceleration is g=9.8m/s^2 and the density of water is =1000kg/m^3:

Find the hydrostatic force on a square steel plate with sides 3m placed vertically.

## Homework Equations

Pressure=[tex]\rho[/tex]gd

F=Pressure * Area

## The Attempt at a Solution

For pressure I did P=(1000kg/m^3)(9.8m/s^2)(25m)= 245000

Then, did Force=(245000 Pa)(3m * 3m)=2205000 N and it was the wrong answer.

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