LET THE MAN PULL IT BY A FORCE F THEREFORE THERE WILL BE  TENSION IN THE STRING WHOSE MAGNITUDE WILL BE F

THE WEIGHT RECORDED BY THE MACHINE WILL BE N AND ACCORDING TO EWTONS 3 RD LAW AND THE FIGURE IT WILL ACT IN THE UPWARDS DIRECTION

 

THE FBD OF THE MAN

N+T-60g=A (SINCEW IT IS NOT ACC)

HERE N IS THE FORCE EXERTED BY THE WEIGHING MACHINE 

THE FBD OF THE BLOCK

T-N+=30g

 

SOLVING IT WE GET

2T=90

T=45G

N=15G

THIS  IS THE ACTUAL WEIGHT RECORDED BY THE MACHINE

 

2ND PART

SINCE A FORCE OF 45G IS TO RECORD A WEIGHT OF 15G

THEREFORE TO RECORD A WEIGHT OF 60G A FORCE OF

45*4G=180G=1800N AHAS TO BE APLIED

 

ANOTHER METHOD

2ND PART OF THE QUESTION

IT SHOULD BE NOTED THAT THIS TIME THERE WIL BE ACC IN THE LIFT

T+N-60G=60 A    (HERE N =60G)

T=60A

 

T-N=30G

60A-60G-30G=30A

30A=90G

A=3G

T=60A

=180G

=1800N

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