Question

A body of a mass 40 kg stands on a weighing machine in an accelerated lift. The
reading on the scale of the weighing machine is 300 N. Find the magnitude and
direction of acceleration.
(a) 2.3 m/s2 upwards
(b) 2.3 m/s2 downwards
(C) 4.6 m/s2 upwards
(d) 4.6 m/s2 downwards​

Answer 1

Given :- Mass of the body =m1 =40kg

Weight =300N

The reading in weighing machine is 300N

∴ The mass shown on weighing machine is calculated as,

w=m2g

∴300=m² ×9.8

∴m²=30.61kg

The mass (m2 ) shows that it is less than the actual mass (m1 ) of the body, Therefore the mass is decreased, hence we say that the lift is accelerating downwards direction. Because the weight decrease when lift is moving downwards.

∴ The Tension in cable when lift is accelerating downwards is,

∴T=m2g−m1a

T=m1 (g−a)

∴300=40(9.8−a)

=9.8−a

∴a=9.8−2.15

∴a=2.3m/²

∴ Lift is accelerating downwards with acceleration

∴ Option B is correct