- #1

tracker890 Source h

- 90

- 11

- Homework Statement
- To determine F

- Relevant Equations
- moment balance equation

Please help me to understand why it is wrong to take moment for point ## A’ ## , because I think static equilibrium should be static equilibrium for any point in space.

Method 1：

$$ \sum{M_A=0:} $$

$$ F\cdot R=\left( F_p \right) _x\cdot \left( R-y_p \right) +\left( F_p \right) _y\left( x_p \right) $$

$$ F=\frac{1}{R}\left[ \left( F_p \right) _x\cdot \left( R-y_p \right) +\left( F_p \right) _y\left( x_p \right) \right] ..........\text{(}Ans\text{)} $$

Method 2：

$$ \sum{M_A’=0:} $$

$$ F\cdot R=\left( F_p \right) _x\cdot \left( R-y_p \right) $$

$$ F=\frac{1}{R}\left[ \left( F_p \right) _x\cdot \left( R-y_p \right) \right] ...........\left( wrong\ answer \right) $$