Free body diagram of man in a box

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SUMMARY

The discussion revolves around a physics problem involving a 60 kg man standing in a 30 kg box on a weighing machine. The key question is determining the weight displayed by the machine when the box is at rest due to the man's force applied via a rope. The correct answer is 15 kg, as indicated in the textbook, which suggests that the net force acting on the system must be analyzed using free body diagrams for both the man and the combined man-box system.

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Homework Statement


A 60 kg man stands in a 30 kg box on a light weighing machine.
If the box is kept at rest due to force applied by the man by the rope , what is the weight shown by the weighing machine?


Homework Equations





The Attempt at a Solution


.answer given in book is 15 kg.
But if the net force man i think will his weight-weight of the box=300N
I don't think i am proceeding correctly.
I just need a hint for the free body diagram.
Thanks in advance
 

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hi 1/2"! :wink:

as often in these problems, you need two free body diagrams …

in this case, one for the man (on his own), and one for the man-and-box …

how many external forces forces are there in each case? :smile:​
 

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