IIT JEE , AIEEE Forum - Physics , Mechanics

amitshivani

hc verma q 39

Greatdreams

Mass of man = 60 g

Mass of box = 30 g

Let R' be the app wt of man and T be the correct wt

R' + T = 60 g

T - R' = 30 g

R' = 15 g

So wt shown by machine = 15 g

Let the wt applied to get correct wt. be T and R be the normal reacn.

Considering Free body diagram of man,

T + R = 60(g +a) : a = accn of lift

Fbd of box,

T - R = 60(g - a)

So R = 60 g

T = 60 a

But T = 90 g + 30 a

90 g + 30 a = 60 a

a = 3g

So T = 1800 N

Hope the thing is clear

Pls do rate me

ramyani