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Question Set: Pressure
NGSS Crosscutting Concepts
NGSS Disciplinary Core Ideas
Table of Contents
  1. At sea level, the density of fresh water at 4˚C is 1.000 g/cm3, and the density of seawater at 4˚C is 1.028 g/cm3. What is the water pressure at the bottom of a column of ten 1 cm cubes of fresh water? Of seawater?
  2. Aquaria vary greatly in size, shape, and purpose. Calculate the pressures at the bottom of
    1. a 10 L saltwater display aquarium filled to a depth of 1 m.
    2. a 10 L saltwater fish breeding tank filled to a depth of 20 cm.
    3. the Monterey Bay Aquarium's kelp forest display tank, which is 9.5 m (31 ft) high with a water depth of 8.5 to 8.6 m (28 ft) and a volume of 1,326,500 L (350,000 gal) of seawater.
  3. Another unit used by engineers to measure pressure is pounds per square inch (psi) where 1 atm = 14.7 psi, and 1 psi = 0.06804 atm. Using this information, calculate the pressure in psi of the aquaria described in question 2.
  4. At the surface, a free diver’s lungs are filled with 5 L of air.
    1. What is the volume of air in their lungs at 10 m? Describe what happens to the air as they descend.
    2. To what depth would a person have to descend to reduce lung volume from its normal volume at sea level to one-third that volume?
  5. Some fish have a swim bladder—a gas-filled space that controls buoyancy.
    1. If a fish with a swim bladder swam into a net at a depth of 40 m and an aquarium collector quickly hauled it to the surface, what might happen to it? What do you think could be done to minimize harm to these types of fish if the collector wanted to keep them alive?
    2. Crabs and lobsters do not have swim bladders. How do you think hauling them up from a depth of 40 m would affect them?
  6. Explain how water pressure affects a diver’s eardrums. Make a sketch as part of your answer.
  7. Explain how pressure changes affect our ears
    1. when we drive up a mountain.
    2. when we drive down a mountain.
  8. What do you think could happen to a diver on the way back to the surface if the opening to the nasal sinuses became blocked?
  9. Years ago airplane passengers were given chewing gum before the flight took off. Why do you think airlines did this? Why do you think airlines discontinued this practice?
  10. Based on your knowledge of Boyle’s Law, complete table 9.3 for a one-liter tube with an opening on the bottom similar to the one shown in Figure 9.14. Remember that at each depth, air pressure inside the tube equals the hydrostatic pressure outside the tube. Explain how your calculations change as pressure is increased.
  11. Based on the data from Question 10, make a graph of water depth (X axis) vs. gas volume (Y axis). At which of these intervals does the greatest change in air volume take place? Why?
    1. from surface to 10 m
    2. 10 m to 20 m
    3. 20 m to 30 m
    4. 30 m to 40 m


Table 9.3. Table of the effect of increasing depth on the volume of an open one-liter tube



Water pressure


Pressure in air tube


Volume of air in the tube




Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.