🔍 Key Concepts

• Hydrostatic pressure and how water naturally flows from higher to lower levels • Difference between tanks above the waterline and tanks below the waterline in terms of gravity flow • What operations require positive pressure from a pump versus what can be done by simply opening a valve

💭 Think About

• Think about when you open a drain on a container of water: under what condition will the water flow out by itself without any help? • For each option, picture the tank’s water level relative to the sea surface. In which case will gravity or outside water pressure do all the work? • Which operations involve moving water into a space against pressure, and which involve just letting water go where it already ‘wants’ to go?

✅ Before You Answer

• Identify which option involves water leaving a space that is already at a higher level than where it’s going • Check whether sea pressure is pushing water in or whether gravity is letting water out • Confirm if any choice would require overcoming external water pressure or lifting water upward, which would mean a pump is needed