Question

name of physical quantity whose unit is watt second

Answer 1

energy is physical quantity whose unit is watt second

Answer 2

The watt-second is the energy equivalent to the power of one watt sustained for one second. While the watt-second is equivalent to the joule in both units and meaning, there are some contexts in which the term "watt-second" is used instead of "joule".

Hope this will help you!!!
☺☺ Keep smiling ☺☺