(i) Distinguish between thrust and pressure.
(ii) Why is it easier to swim in sea water than in river water?
(i) Thrust The total perpendicular force exerted by a body on any surface in contact with it, is called thrust.
Pressure The thrust acting per unit area of a surface is called pressure.
(ii) It is easier in sea water because sea water exerts more upthrust on the body than the river water because of its higher density.