In the given figure mass of string `AB` is `2kg`. Find tension at `A,B` and `C`, where `C` is the mid point of string.

Explanation

`a =(F-"weight of 2kg -weight of 4kg -weight of string")/("mass of 2kg +mass of 4kg +mass of string")`
`=(100-20-40-20)/(2+4+2)` `(g =10m//s^(2))`
`=(20)/(8) =25 ms^(2)`
Refer Fig.(a) `T_(A)-m_(AB)g-40=(m_(AB)+4)a`
or `T_(A)-20-40=(2+4)(2.5)`
`T_(A)=75N`

Refer Fig.(b) `T_(c)-m_(BC)g-40=(m_(BC)+4)a`
or `T_(C)-10-40=(1+4)(2.5)`
`T_(C)=62.5N`
Refer Fig.(c) `T_(B)-40=4a`
or `T_(B) =40+4xx2.5`
`T_(B) =50N`