Q149
General SciencePhysics
A boat floating in a tank is carrying some passengers. If the passengers drink water from the tank, how will it affect the water level of the tank?
- a.It will go down.
- b.It will rise.
- c.It will depend on the atmospheric pressure.
- d.It will remain same.
Answer: (D) It will remain same.
A floating boat displaces water equal in weight to the total load it carries. If the passengers drink a mass $m$ of water from the tank, the tank loses a volume $\frac{m}{\rho}$, but the boat becomes heavier by $m$ and displaces exactly $\frac{m}{\rho}$ more water - the two effects cancel and the level stays the same. Compare the classic variants: a stone thrown from the boat into the water - level falls; ice floating in water melts - level unchanged. Atmospheric pressure plays no role.