Question Number 151096 by john_santu last updated on 18/Aug/21
$$ \\ $$find the center of gravity with respect to point O
Commented by john_santu last updated on 18/Aug/21
Commented by Olaf_Thorendsen last updated on 18/Aug/21
$$\bullet\:\mathrm{A}\:\mathrm{big}\:\mathrm{full}\:\mathrm{square}\:: \\ $$$$\mathrm{S}_{\mathrm{1}} \:=\:\mathrm{10}×\mathrm{10}\:=\:\mathrm{100}\:\mathrm{cm}^{\mathrm{2}} \\ $$$$\Omega_{\mathrm{1}} \left(\mathrm{5},\mathrm{5}\right) \\ $$$$ \\ $$$$\bullet\:\mathrm{A}\:\mathrm{small}\:\mathrm{empty}\:\mathrm{rectangle}\:: \\ $$$$\mathrm{S}_{\mathrm{2}} \:=\:−\mathrm{4}×\mathrm{2}\:=\:−\mathrm{8}\:\mathrm{cm}^{\mathrm{2}} \\ $$$$\Omega_{\mathrm{2}} \left(\mathrm{8},\mathrm{3}\right) \\ $$$$ \\ $$$$\bullet\:\mathrm{A}\:\mathrm{small}\:\mathrm{empty}\:\mathrm{rectangle}\:: \\ $$$$\mathrm{S}_{\mathrm{3}} \:=\:−\mathrm{4}×\mathrm{2}\:=\:−\mathrm{8}\:\mathrm{cm}^{\mathrm{2}} \\ $$$$\Omega_{\mathrm{3}} \left(\mathrm{8},\mathrm{7}\right) \\ $$$$ \\ $$$$\mathrm{S}\:=\:\mathrm{S}_{\mathrm{1}} +\mathrm{S}_{\mathrm{2}} +\mathrm{S}_{\mathrm{3}} \:=\:\mathrm{100}−\mathrm{8}−\mathrm{8}\:=\:\mathrm{84}\:\mathrm{cm}^{\mathrm{2}} \\ $$$$ \\ $$$$\mathrm{S}\overset{\rightarrow} {\mathrm{OG}}\:=\:\mathrm{S}_{\mathrm{1}} \overset{\rightarrow} {\mathrm{O}\Omega_{\mathrm{1}} }+\mathrm{S}_{\mathrm{2}} \overset{\rightarrow} {\mathrm{O}\Omega_{\mathrm{2}} }+\mathrm{S}_{\mathrm{3}} \overset{\rightarrow} {\mathrm{O}\Omega_{\mathrm{3}} } \\ $$$$\overset{\rightarrow} {\mathrm{OG}}\:=\:\frac{\mathrm{100}}{\mathrm{84}}\left(\mathrm{5},\mathrm{5}\right)−\frac{\mathrm{8}}{\mathrm{84}}\left(\mathrm{8},\mathrm{3}\right)−\frac{\mathrm{8}}{\mathrm{84}}\left(\mathrm{8},\mathrm{7}\right) \\ $$$$\mathrm{G}\left(\frac{\mathrm{31}}{\mathrm{7}},\mathrm{5}\right) \\ $$
Commented by john_santu last updated on 18/Aug/21
$$\mathrm{how}\:\mathrm{to}\:\mathrm{get}\:\Omega_{\mathrm{1}} \left(\mathrm{5},\mathrm{5}\right)\:. \\ $$
Commented by Olaf_Thorendsen last updated on 18/Aug/21
$$\mathrm{the}\:\mathrm{square}\:\mathrm{is}\:\mathrm{10}×\mathrm{10}. \\ $$$$\mathrm{the}\:\mathrm{center}\:\mathrm{of}\:\mathrm{gravity}\:\mathrm{is}\:\left(\mathrm{5},\mathrm{5}\right). \\ $$