It is easier to swim in sea water than in a river because, the sea water contains salt which increases the density of water and also increases its upthrust so, the body sinks less in it and we swim easily ...
Archimedes principle, the weight of water displaced by any
body equals the weight of the floating body. In sea water,
as density is more, less volume of water has to be displaced
for a swimmer to float. Hence, it is easier to swim.
The magnitude of electrostatic force between two identical
positive ions that are separated by a distance of 5.0 x 10–
10 m is 3.7 x 10–9 N. (a) What is the charge of each
ion? (b) How many electrons are “missing” from each ion?