Final answer:
The water pressure is greatest at the point where the diver is located, at 20 feet deep, due to the additional weight of the water and atmospheric pressure above them. Divers must manage pressure changes to avoid injury.
Step-by-step explanation:
Regarding the question 'Where is the water pressure greatest when a diver is practicing diving at a 20ft depth in a diving pool?', the answer is: a) Where the diver is. Water pressure increases with depth due to the weight of the water above. At 20 feet deep, the water pressure felt by the diver will be greater than it is closer to the surface, because there is more water above them, exerting pressure. Additionally, the atmospheric pressure from the air above the water also contributes to the total pressure experienced by the diver. For every 33 feet of salt water, 1 atmosphere absolute (ATA) of pressure is added to the atmospheric pressure at sea level. Therefore, at 20 feet, the pressure is not a whole additional ATA but a proportion of it. In any case, the pressure increases as the diver goes deeper and is greatest at their current depth compared to any point above them. Still, divers must be aware of the changes in pressure to prevent any injury such as ear drum rupture or lung overexpansion. This is managed through techniques such as equalization and the controlled use of a buoyancy compensator (BCD).