How much pressure will man of weight 60 kg exert on the ground when (a) he is standing on his feet and (b) he is lying on ground. Given that the area of a foot is `100cm^(2)` and areaa of the body of a man in contact with ground =`0.6 m^(2)`. Use `g=10m//s^(2)`

Explanation

Here, force of man on ground is
`F=Mg=60 xx 10 = 600N`,
(a) When man is standing on his feet, area of feet in contact with ground , A=`2 xx 100 = 200 cm^(2)`
`=200 xx 10^(-4) m^(2)`
Pressure, `P=F/A = (600)/(200 xx 10^(-4))=3xx10^(4)Pa`.
(b) when man is lying on ground , the area of man in contact with ground , `A=0.6 m^(2)`
Pressure, `P=F/A = (600)/(0.6) = 10^(3) Pa`.