Question

a body of mass 40kg stands on weighing machine in a accelerated lift. the reading on the scale of the weighing machine is 300N. find the magnitude and direction of acceleration

Answer 1

m=40kg

F=300N

suppose that g=9.8m/s²

Now, when the lift goes down, 2 types of accelerations are applied,

1. gravitational acceleration

2.acceleration of life

By thinking about the FBD of the lift,

if the lift moves down, the sum of acceleration = g-a

and if it moves up, it is g+a

[why? Becuase when the life moves, an illusory acceleration is applied on it, which is 'a' here]

That means,

1. if the lift is moving upwards,

F=m(g+a)

300=40(10+a)

a= -2/5 m/s²

2. if lift is going down,

F=m(g-a)

300=40(10-a)

a= +2/5 m/s²

Now the directions:

1.if the lift moves downwards, the magnitude of acceleration is +2/5 m/s²

2.if the lift moves downwards, the magnitude of acceleration is -2/5 m/s²

Hope it helps

If it does please mark me as the brainliest.☆☆☆☆

Answer 2

F = mg - ma

300 = 393 - 40a

-40a = -92

a =. 92÷40

= 2.3 m/s upwards