Apparent Weight Of Body In A Lift - Practice Questions & MCQ

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_{n e t}=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, } \\
& \begin{array}{l}
a<g \\
R-m g=m a \\
R
\end{array} \\
& R(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)