Question

A person is standing on a weighing machine placed on the floor of an elevator. The elevator starts going up with some acceleration, moves with uniform velocity for a while and finally decelerates to stop. The maximum and minimum weights recorded are 72 kg and 60 kg. Assume that the magnitude of the acceleration and the deceleration are the same, find the magnitude of the acceleration. Take $g=9.9m{s}^{-2}$

• A. $2.9m{s}^{-2}$
• B. $9.9m{s}^{-2}$
• C. $1.6m{s}^{-2}$
• D. $0.9m{s}^{-2}$

Answer 1

Answer: (D)

$0.9m{s}^{-2}$

While going up with acceleration $a$, the apparent weight of the person $=m(g+a)=72g$

While going down with acceleration $a$, the apparent weight of the person $=m(g-a)=60g$

Hence, $\frac{g-a}{g+a}=\frac{60}{72}$

$⟹a=0.9m/s^2$