Define pressure. Give its SI unit.
The total force applied per unit area is called pressure.
Mathematically,
Pressure (P) = Force (F) / Area (A)
Its SI unit is pascal (Pa).
Why is it easier to swim in seawater than in river water?
We know that seawater is found as saline water (salt solution). So, seawater has a higher density than river water. Also, upthrust ∝ density. So, more upthrust is exerted in seawater than in river water. Hence, it is easier to swim in seawater than in river water.