Question

Why it is easy to swim in sea than river, lake or pond ? Explain.​

Answer 1

Answer:

There are two reasons which could apply to this, one of which will always apply.

Positive buoyancy is what is normally known as floating. An object will be positively buoyant if it displaces (pushes aside) a volume of water which weighs more than it does. Sea water contains salt in far higher quantity than fresh water. On average, fresh water weighs 1kg per litre whereas sea water weighs 1.03kg per litre. This means that if the same object, in this case you, gets into sea water you will displaces the same amount of water in terms of volume, but the sea water weighs more meaning that you will be more positively buoyant i.e. you float better. This makes swimming easier.

Current can be another factor. While current is found in both sea water and fresh water it is more likely that you would encounter a more powerful current in a flowing river than at the beach. This is not a rule and it should never be assumed that sea water won't contain current, rip tides (a powerful current dragging out to sea) are deadly and kill people every year. Current requires more effort to swim against than still water.

Answer 2

Answer:

Answer: It is because sea water contains more amount of salt as compared to river/fresh water as a result its density increases and hence the buoyant force increases which makes it easier to swim in sea water.