A man of mass `60kg` is standing on a massless weighing machine. Find the weight of the man in different situations as shown in the following figures.

Man holds the rope and the block is at rest.

Man holds the rope and the system is at rest.

Man holds the rope and the system is at rest.

Explanation

(a) Man`:`
`N_(0)=600=60a=60xx2`
`N_(0)=720N`
`N_(0)=W'=720N`
Weight shown by the machine `=720N`
(b) Block`:`

`T=500=0rArrT=500N`
Man`:`

`T+N_(0)-600=0rArrN_(0)=100N=W'`

Man`:`

`T+N_(0)=600`
Plank`:`

`2T+T-N_(0)=0`
From (ii),`T=(N_(0))/(3)` in (i)
`N_(0)+(N_(0))/(3)=600rArrN_(0)=450N`
Weight shown by the machine `=450N`
(d)
Man`:`

`T+N_(0)-600=0`
Box`:`
`T-N_(0)-300=0` (ii)
From (i) and (ii), `N_(0)=150N`
Weight shown by the machine`=150N`