Question

A boy stands on a weighing machine inside a lift. When the lift is going down with acceleration g/4

Answer 1

When the lift is going in downward direction with an acc. of g/4, net acc. of the lift

g`=g-g/4=3g/4. Weight of the body=mg`=m3g/4

Now the weight of the body is due to the normal reaction of the floor if the lift which is

N=mg`=3mg/4

3mg/4=30

m=12

Now when the lift is going up with an acc. of g/4 then net acc. is g+g/4=5g/4

N=m5g/4

N=12*5*10/4=150kg