A passenger of mass 72.2 kg is riding in an elevator while standi… - Vidyadip

Question

A passenger of mass $72.2\ kg$ is riding in an elevator while standing on a platform scale. What does the scale read when the elevator cab is:

Descending with constant velocity,
Ascending with constant acceleration, $3.5\ m/ s$?

✓

Answer

Given, mass, $\mathrm{m}=72.2 \mathrm{~kg}$
Gravity acceleration, $\mathrm{g}=9.8 \mathrm{~m} / \mathrm{s}^2$
Scale reading $=$ apparent weight $=\mathrm{R}= ?$
i. While descending with constant velocity, $\mathrm{a}=0$
$R=m g$
$R=72.2 \times 9.8$
$R=707.56 \mathrm{~N}$
ii. While ascending with $a=3.2 \mathrm{~m} / \mathrm{s}$
$R=m(g+a)$
$R=72.2(9.8+3.2)$
$=938.6 \mathrm{~N}$

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