When a lift is accelerating downward that a=g then the net force acting on the object is: (a)F=0N (b)F=mg (c)F=w-mg (d) F=w_ma

the answers the correct one is A

 F = 0

Explanation:

To find the net force we must apply Newton's second law

           F -W = ma

where the upward direction is positive, they indicate that the acceleration is equal to = - g

           F = W - m g

the weight of a body of W = mg

   we substitute

           F = mg - mg

           F = 0

The check the answers the correct one is A

we need to know the time interval during which the force acts. impulse of force = momentum change