12.
(a) The total weight is
W = ρghA =
1.00
× 10
3
kg/m
3
9.8 m/s
2
(200 m)
3000 m
2
= 6.06
× 10
9
N .
(b) The water pressure is
p = ρgh =
1.03
× 10
3
kg/m
3
9.8 m/s
2
(200 m)
1 atm
1.01
× 10
5
Pa
= 20 atm
which is too much for anybody to endure without special equipment.