Question

When a boat in a river enters the sea water, then it:

• A. sinks a little
• B. rises a little
• C. remains same
• D. will drown

Answer 1

Answer: (B)

rises a little

Sea water is saltier than river water, and hence it has more density.

The buoyant force on boat upwards is given by $V\rho g$

where $V$ is the volume of displaced water and $\rho$ is the density of water.

Clearly the buoyant force is more in case of seawater and hence the boat rises when it goes from river to sea.