Case 1: When the elevator is at rest or moves with uniform velocity

            Acceleration of the person = 0

            Net force on the person F = 0

            i.e. R –mg = 0 or R = mg

            i.e. apparent weight is equal to the actual weight of the person.
 

Case 2: When the elevator is accelerating upwards

            Suppose uniformly upward acceleration of the person in the elevator is ‘a’

            or R₁ = mg + ma = m (g +a ) . …..(i)

Hence apparent weight of the person becomes more than the actual weight, when the elevator is accelerating upwards.

 
Case 3: When the elevator is accelerating downwards

            Suppose uniform downward acceleration of the person in the elevator = a

            R₂ = mg – ma = m (g –a) …….(ii)

            Thus R₂ < mg

Hence apparent weight of the person becomes less than the actual weight when the elevator is accelerating downwards.

Case 4: In free fall of a body under gravity, a = g

            Therefore, R₂ = m (g-g) = 0

            i.e. apparent weight of the person becomes zero or the body becomes
            weightless.

 
Case 5: When downward acceleration is greater than g.

i.e. a > g, then R₂ = m (g-a), R₂ becomes negative. In that event, the person will rise from the floor of the elevator and stick to the ceiling of the lift.
 

Question 1. In tug of war, if one team exerts a force on the second team, then the second team also exerts an equal and opposite force on the first. Then how is it possible that one team wins?

Ans. The team which exerts a greater force on the ground gets greter reaction from the ground and is able to win.