Question

Account for the following:- It is easier to swim in sea water than in a river water.

Answer 1

1. An object will float in a fluid if the density of the object is lesser than that of the fluid.
2. An object will sink into a fluid if the density of the object is greater than that of the fluid.
3. The density of saltish seawater is $(1030\raisebox{1ex}{$kg$}\!\left/ \!\raisebox{-1ex}{$m^3$}\right.)$ but the density of fresh water is only$(1000\raisebox{1ex}{$kg$}\!\left/ \!\raisebox{-1ex}{$m^3$}\right.)$.
4. As a result, A swimmer experiences a greater upthrust in seawater and it is easier for him to swim in seawater than in river water.