Pressure in water and ecological balance
Answers are for parents and teachers.
1
At what depth is the total pressure 9 atm?
Water adds 9 − 1 = 8 atm, so the depth is 8 × 10 = 80 m.
2
A pressure of 4.5 × 10⁵ N/m² acts on a surface of 0.25 m². Find the force.
F = 4.5 × 10⁵ × 0.25 = 112 500 N.
3
Give two differences between bony and cartilaginous fish.
Bony fish have a bone skeleton and a swim bladder; cartilaginous fish have a lighter, more flexible cartilage skeleton and no swim bladder.
4
Why are deep-sea animals not crushed by the pressure?
They have no large gas-filled spaces, and their body fluids are at the same pressure as the water outside.
5
Write a chain of three steps showing how overfishing of predators can change a food chain.
Fewer predatory fish; more small fish; less zooplankton (and so more algae).