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An air bubble originating from an under water diver has a radius of 4 mm at some depth h. When the bubble reaches the surface of the water, it has a radius of 7 mm. Assuming the temperature of the air in the bubble remains constant, determine the absolute pressure at this depth h. The acceleration of gravity is 9.8 m/s² . Answer in units of Pa.

User Danielemm
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Final answer:

Using Boyle's Law, the absolute pressure at depth h for the underwater bubble is calculated to be approximately 549,545 Pascals.

Step-by-step explanation:

The question asks to calculate the absolute pressure at a certain depth in water when an air bubble increases in radius from 4 mm to 7 mm, assuming the temperature remains constant. We can use Boyle's Law, which states that the pressure of a given mass of an ideal gas is inversely proportional to its volume when the temperature stays constant (P1V1 = P2V2). The air bubble's volume at depth is (4/3)π(0.004 m)³ and at the surface is (4/3)π(0.007 m)³. The absolute pressure at the surface is 1 atmosphere, which can also be expressed as 101,325 Pa.

To find the pressure at depth, we'll set up the equation as follows: P1 * (4/3)π(0.004 m)³ = P2 * (4/3)π(0.007 m)³. Because we know P2 (absolute pressure at the surface), we can solve for P1 (absolute pressure at depth).

Substituting the given values and solving for P1 yields:

P1 * (4/3)π(0.004 m)³ = 101,325 Pa * (4/3)π(0.007 m)³

P1 = 101,325 Pa * ((0.007 m)³ /(0.004 m)³)

P1 = 101,325 Pa * (7/4)³

P1 = 101,325 Pa * (343/64)

P1 = 549,545 Pa

Therefore, the absolute pressure at depth h is 549,545 Pascals.

User Markus Kull
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