Solve Pressure Problem: Upward Force for Ocean Hatch

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To determine the upward force required to open a hatch of area 0.75 m² at a depth of 30 meters in the ocean, the internal pressure of 1 atmosphere must be considered alongside the pressure exerted by the water. The relevant equation combines atmospheric pressure and hydrostatic pressure: P = Patm + ρgh. The upward force can then be calculated using F = P*A, where P is the total pressure acting on the hatch. The approach discussed in the thread is correct for solving the problem.
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Homework Statement


A submersible with internal pressure of 1 atmosphere is at a depth of 30 meter below the surface of the ocean. At this depth, what is the upward force required to open a hatch of area 0.75 m2. Assume density of sea water is 1030 kg/m3.

Homework Equations


P = Patm + ρgh
F = P*A

The Attempt at a Solution


Do I have to add the atmospheric pressure on the surface of the ocean? I have this equation : Patm + ρgh = Pinternal + P2
then F = P2 * A.
is this approach right?
 
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tommyhakinen said:
is this approach right?

Yes, looks good.

p.s. Welcome to PF.
 
Thank you..
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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