Q 11-04-170JEE MainJEE Main 2021 (26 Feb, Shift 1)Easy
A person standing on a spring balance inside a stationary lift measures $60$ kg. The weight of that person if the lift descends with uniform downward acceleration of $1.8$ m s$^{-2}$ will be ______ N. $[g = 10\ \text{m s}^{-2}]$
Numerical value type. Enter your answer.
Answer: 492
For downward acceleration $a$, the normal force (reading) is $N = m(g - a)$.
$$N = 60(10 - 1.8) = 60\times8.2 = 492\ \text{N}$$
Solution by Sreeraj P, M.Sc Physics