Question

A submarine dives to a depth of 232 feet in the ocean. What is the force (in pounds) acting on a hatch that has an area of 4.3 square feet? WARNING: do not use the information associated with Figure 4.26 to solve this problem because the round off error will cause you to get the wrong answer. Do not consider atmospheric pressure in your calculation, since the pressure inside of the submarine is maintained at 1 atmosphere, which offsets the 1 atmosphere of pressure that normally would be added to the gauge pressure

Answer 1

Answer 2

rho xgxh xA = 62.4 lb/ft3 x 32.174 x 232 x 4.3 = 200.2839222 x10^4 lbft/s^2

Answer 3

delta P = P - Po

= rho*g*h

= 1030*9.8*232*0.3048

= 713783.0784 N/m^2

F = delta P*A

= 713783.0784*4.3*(0.3048)^2

= 285144.26 N

= 285144.26/0.454

= 628071 lb

Answer 4

1 feet =0.3048 m

so depth

h=232*0.3048 =70.7 m

1 feet² =0.0929 m²

A=4.3*0.0929=0.4 m²

density of sea water

p=1025 kg/m²

Pressure at this depth is

P=P_o+pgh =1*10⁵+1025*9.8*70.7

P=8.1*10⁵ pascal

Force exerted

F=PA =8.1*10⁵*0.4

F=3.24*10⁵ N