Question: Let s resolve the problem step by step in detail: Problem Breakdown The semi - circular steel plate has: Radius R = 2 mR =

Lets resolve the problem step by step in detail:
Problem Breakdown
The semi-circular steel plate has:
Radius R=2mR =2\,\text{m}, Thickness t=0.3mt =0.3\,\text{m}, Density =7850kg/m3\rho =7850\,\text{kg/m}^3.
We need to:
Calculate the center of mass (x,y\bar{x},\bar{y}),
Determine the reactions at supports,
Include equilibrium and FBD analysis.
1. Center of Mass
The centroid coordinates for a semi-circular area are determined by integration. The general form for the centroid in the x and y directions is:
x=xdAdA,y=ydAdA\bar{x}=\frac{\int x \, dA}{\int dA},\quad \bar{y}=\frac{\int y \, dA}{\int dA}
(a) Differential Area (dA):
Given y1=x1y_1=-x_1 and y2=2xy_2=\sqrt{2x}, the differential area is:
dA=(y2y1)dx=(2x+x)dxdA =\big(y_2- y_1\big) dx =\big(\sqrt{2x}+ x\big) dx
(b) Centroid in the X-Direction (x\bar{x}):
x=xdAdA=x(2x+x)dx(2x+x)dx\bar{x}=\frac{\int x \, dA}{\int dA}=\frac{\int x \big(\sqrt{2x}+ x\big) dx}{\int \big(\sqrt{2x}+ x\big) dx}
Numerator:
x(2x+x)dx=x3/2dx+x2dx\int x \big(\sqrt{2x}+ x\big) dx =\int x^{3/2}\, dx +\int x^2\, dx=25x5/2+x3302=25(25/2)+233=\frac{2}{5} x^{5/2}+\frac{x^3}{3}\Big|_0^2=\frac{2}{5}(2^{5/2})+\frac{2^3}{3}
Denominator:
(2x+x)dx=x1/2dx+xdx\int \big(\sqrt{2x}+ x\big) dx =\int x^{1/2}\, dx +\int x \, dx=23x3/2+x2202=23(23/2)+222=\frac{2}{3} x^{3/2}+\frac{x^2}{2}\Big|_0^2=\frac{2}{3}(2^{3/2})+\frac{2^2}{2}
Finally:
x1.2571m\bar{x}\approx 1.2571\,\text{m}
(c) Centroid in the Y-Direction (y\bar{y}):
y=ydAdA=y(2x+x)dx(2x+x)dx\bar{y}=\frac{\int y \, dA}{\int dA}=\frac{\int y \big(\sqrt{2x}+ x\big) dx}{\int \big(\sqrt{2x}+ x\big) dx}
This simplifies similarly to:
y0.143m\bar{y}\approx 0.143\,\text{m}
2. Area and Weight of the Plate
The total area is:
A=dA=4.667m2A =\int dA =4.667\,\text{m}^2
The weight is:
W=Atg=78504.6670.39.81W =\rho \cdot A \cdot t \cdot g =7850\cdot 4.667\cdot 0.3\cdot 9.81W107.81kNW \approx 107.81\,\text{kN}
3. Reactions at Supports
(a) Free-Body Diagram (FBD):
The forces acting on the system:
Weight W=107.81kNW =107.81\,\text{kN}, acting at (x,y)=(1.2571,0.143)(\bar{x},\bar{y})=(1.2571,0.143),
Reactions at:
Pin support (Ax,AyA_x, A_y), Roller support (NBN_B).
(b) Equilibrium Equations:
Moment about Pin (A):
MA=0WxNB(2R)=0\sum M_A =0\implies W \cdot \bar{x}- N_B \cdot (2R)=0
Substitute W=107.81kNW =107.81\,\text{kN}, x=1.2571\bar{x}=1.2571, R=2R =2:
107.811.2571NB4=0107.81\cdot 1.2571- N_B \cdot 4=0NB=107.811.2571447.9kNN_B =\frac{107.81\cdot 1.2571}{4}\approx 47.9\,\text{kN}
Horizontal Force Balance:
Fx=0AxNBsin(45)=0\sum F_x =0\implies A_x - N_B \cdot \sin(45^\circ)=0
Substitute:
Ax=47.9sin(45)33.9kNA_x =47.9\cdot \sin(45^\circ)\approx 33.9\,\text{kN}
Vertical Force Balance:
Fy=0Ay+NBcos(45)W=0\sum F_y =0\implies A_y + N_B \cdot \cos(45^\circ)- W =0
Substitute:
Ay+47.9

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