Question

1. A personal submarine is designed to withstand a pressure of 30.4 x 106 Pa. If the density of sea water is r = 1030 kg/m3 and the pressure at the surface of the water is 101.3 kPa determine the maximum depth the submarine can go before very bad things begin to happen.

2. Air in a tornado blows over the horizontal roof of a house (built by CE&C, Inc., famous for cutting costs and losses) with a speed of 117 m/s (approximately 262 mph). The roof has an area of 121 m2, a thickness of 5 cm and is constructed of ultrasuperpolyfoam board with a density of 0.05 g/cm3. If each nail can withstand a maximum force of 1400 N, what minimum number of nails is required to keep the roof in place under the conditions described? (Note: the density of air is 1.29 kg/m3, the house is completely sealed to outside air, and atmospheric pressure is 101.3 kPa.)

Answer 1

1)

Here,we have the maximum withstanding pressure of the personal submarine given by,

Given that,Density of the sea water,

Pressure at the surface of water,

So,By Pascals law,the pressure at a depth in a liquid of density ,if the pressure at the surface is is given by,

Here,let The depth at which the pressure becomes the maximum withstandable pressure of will leads submarine to happen bad things or damage.

So applying Pascal's law,

ie,

So,the maximum depth submarine can go safely is .

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