Final answer:
The pressure at point A under 9 m of water is determined by calculating the pressure from the water column using the formula ρgh and adding it to the atmospheric pressure of 1.00 atm.
Step-by-step explanation:
The pressure at point A, located 9 m under the surface of a lake, can be determined by adding the atmospheric pressure to the pressure exerted by the water above point A. Since the atmospheric pressure is given as 1.00 atm, we only need to calculate the pressure due to the water column.
To find the pressure due to the 9 m depth of water, we use the equation P = ρgh, where ρ is the density of water (approximately 1000 kg/m³), g is the acceleration due to gravity (9.8 m/s²), and h is the depth of the water. After calculating this pressure, we convert it to atmospheres and add 1.00 atm (the atmospheric pressure) to get the total pressure at point A.