Apparent Weight Of Body In A Lift MCQ - Practice Questions with Answers

If mass m is placed on a weighing machine which is placed in the lift.

Actual weight = mg

Apparent weight = Reaction force

R - Reaction force is given by reading of weighing machine.

1. Lift is at Rest

$\begin{aligned} & V=0, a=0 \\ & \text { use } F_{\text {net }}=m \vec{a} \\ & R-m g=0 \\ & R=m g\end{aligned}$

 Apparent weight  = Actual weight

2. Lift is moving upward or down with constant Velocity

$\begin{aligned} & v=\text { const }, a=0 \\ & R=m g\end{aligned}$

 Apparent weight  = Actual weight

3. Lift is accelerating Upward with acceleration = a

$\begin{aligned} & v=\text { variable, } \\ & a<g \\ & R-m g=m a \\ & R=m(g+a)\end{aligned}$

       Apparent weight > Actual weight

4. Lift is moving up with a = g

$\begin{aligned} & R-m g=m g \\ & R=2 m g\end{aligned}$

Apparent weight = 2 (Actual weight)