Question

The mass of a body indicated by a weighing machine in a lift at rest is found to be $m$. If the lift is going down with an acceleration $a$, then the new reading shown by the scale will be $(\text{consider}a<g)$

• A. $m(1-\frac{a}{g})$
• B. $m(1+\frac{a}{g})$
• C. $m$
• D. Zero

Answer 1

The correct option is A $m(1-\frac{a}{g})$

Here it is given that, lift is moving up
Net Normal reaction is

$N=m(g-a)$
mass measured $=\frac{N}{g}=\frac{m(g-a)}{g}$
$=m(1-\frac{a}{g})\text{kg}$

Hence option A is the correct