Practice question · Multiple choice
You float in a boat on a small pond, holding a heavy anchor. You throw the anchor overboard and it sinks. What happens to the pond’s water level?
Hints
- In the boat, the anchor floats with you: it displaces its weight in water. On the bottom, it displaces only its volume.
- For a sinking object, weight-worth of water is more volume than the object itself. Compare the two displacements.
Show the answer
D. It falls slightly
Why
Aboard, the anchor forces the boat to displace water equal to the anchor’s weight, a large volume, since water is less dense. Sunk, it displaces just its own smaller volume. Displacement shrinks, so the pond level drops. Archimedes beats intuition here.
Practise Fluid Statics: Pressure and Buoyancy
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