Question

A person of mass 50 kg stands on a weighing scale on a lift. If the lift is descending with a downward acceleration of 9 ms^–2, what would be the reading of the weighing scale? (g = 10 ms^–2)

Answer 1

When a lift descends with a downward acceleration the apparent weight of a body of mass m is given by w' = R = m(g – a)

Mass of the person m = 50 kg

Descending acceleration a = 9 m/s²

Acceleration due to gravity g = 10 m/s²

Apparent weight of the person,

R = m(g – a)

= 50(10 – 9)

= 50 N

∴ Reading of the weighing scale = `R/g = 50/10` = 5 kg.