Question

why the work done by a normal force on a systam alwYs zero

Answer 1

beacause the angle between the force and displacement is 90
w= fd sinQ
Q=90
so, w= 0

Answer 2

heya dear


here comes your answer

it is bcoz when we apply normal force no object is displaced,

hence work is said to be done when the applied force on an object move from it it's original position.

hope it's help you