Why do you feel lighter when you swim?

Why can you feel a pulse when you keep a finger on the wrist or neck but not when you keep them on a vein?

What do you feel when you thouch a nail immediately after it is hammered into a wooden plank?Why?

Why do you feel giddy while moving on Raatinam (or) Carrousel?

Why do you feel giddy while moving on a merry-go-round ?

Why do we feel light on our feet when standing in a swimming pool with water up to our armptis ?