Passage
During deep underwater dives, scuba divers must overcome the external ambient pressure in order to expand their chests to inhale. To assist underwater breathing, air from scuba tanks is administered at high pressures to keep divers' lungs inflated. Scuba tanks are often filled with a mixture of N₂ and O₂ gas. Due to the increased pressure of the gases in the lungs, a greater amount of the gases are dissolved into the bloodstream during underwater dives. At a body temperature of 37°C, the solubility of N₂ gas in blood is 6.0 × 10⁻³ mol/L⋅atm and the solubility of O₂ gas is 1.3 × 10⁻² mol/L⋅atm.If a diver ascends too quickly after an extended dive, there is an increased risk of vascular bubble formation. Due to the decrease in ambient pressure, the excess gas dissolved in the blood may come out of solution as gas bubbles and cause a number of adverse effects. This condition is known as decompression sickness, or "the bends." To avoid this problem, scuba divers limit their rate of ascension to allow the excess gas dissolved in their blood to be safely removed through respiration. Because gas bubbles are good reflectors of sound, these bubbles can be detected using Doppler ultrasonic flowmetry after the diver has surfaced.
Adapted from M. Spencer, Journal of Applied Physiology. ©1976 American Physiology Society.
-What is the change in pressure when a diver descends from 10 m to 100 m below the water's surface? (Note: The density of water is 1,000 kg/m³.)

Question

Quizplus · Accepted Answer

11ecba2d_12bf_15b3_a3bf_db04a8330390_MD0008_00 Pressure is the force exerted over an area, and hydrostatic pressure is the pressure exerted by the weight of a fluid. The hydrostatic pressure (P) exerted at a point is the product of the fluid's density (ρ), gravitational acceleration (g), and the height (h) of the fluid above it: The pressure experienced by the diver increases with depth because the amount of water directly above increases. During the diver's descent from 10 m to 100 m below the surface, hincreases by 90 m. Using 1,000 kg/m³ for ρ, 10 m/s² for g, and 90 m for Δh, the change in hydrostatic pressure is: The SI unit of pressure is a pascal (Pa), which is defined as one newton per square meter (N/m²). Therefore, this value in scientific notation is 9.0 × 10⁵ N/m². (Choice C) The hydrostatic pressure 100 m below the surface is 1.0 × 10⁶ N/m². However, the diver did not start at the surface; Δh is 90 m, not 100 m. (Choice D) The change in hydrostatic pressure between two points is calculated as a difference, not a sum. The sum of the pressures is 1.1 × 10⁶ N/m². Educational objective: Hydrostatic pressure is the pressure exerted by the weight of a fluid. It is calculated as P = ρgh, where ρ is density, g is the gravitational acceleration, and h is the height of the fluid above the point of interest. The difference in pressure ΔP between two points is calculated using Δh.

Passage During Deep Underwater Dives, Scuba Divers Must Overcome the External