Question

Match the following, according to the state of lift with the apparent weight of any person in lift.

• A. $R>W$
• B. $R=W$
• C. $R<W$
• D. $R=0$

Answer 1

$Case1$: Lift is moving upward with an acceleration ${}^{\prime }{a}^{\prime }$
$R–W=ma\to R=W+ma$
$R=mg+maR=m(g+a)$
$\therefore R>W$

$Case2$: Lift is moving downward with an acceleration ${}^{\prime }{a}^{\prime }$
$W–R=ma\to R=W-ma$
$R=mg-maR=m(g-a)$
$\therefore R<W$

$Case3$: Lift is at rest $a=0$
$R=W$

$Case4$: Lift is falling down freely ($a=g$)
$R=m(g–g)=0$