S.21 2-3

a)
$A=180mm\cdot530mm=95400mm^2=0{,}0954m^2$

$m=68kg$

$g=9{,}81\frac{m}{s^2}$

$p=\frac{F}{A}=\frac{G}{A}=\frac{mg}{A}=\frac{68kg\cdot9{,}81\frac{m}{s^2}}{0{,}0954m^2}=6992{,}45283Pa\approx7000Pa=7{,}0kPa$
V: 7,0kPa.
b)
$A=210cm^2=0{,}021m^2$

$m=68kg$

$g=9{,}81\frac{m}{s^2}$

$p=\frac{F}{A}=\frac{G}{A}=\frac{mg}{A}=\frac{68kg\cdot9{,}81\frac{m}{s^2}}{0{,}021m^2}=31765{,}71429\approx32000Pa=32kPa$
V: 32kPa.