The monkey `B` shown in the figure is holding on the tail of the monkey. A which is climbing up a rope. The masses of the monkeys `A` and `B` are `40kg` and `20kg`, respectively. If `A` can tolerate a tension of `300N` in its fail, what force should it apply on the rope in order to carry the monkey `B` with it?

Explanation

Two possibilities, either monkeys are moving with acceleration or with uniform velocity.
(a) IF tension in the tail is `300N`

`300-20g=20arArra=5m//s^(2)`

`F-40g-300=40a=40xx5`
`F=900N`
(b) If tension in the tail is `200N`, monkeys are moving with uniform velocity.
`F-40g-200=0`
`F=600N`
If monkey `A` applies a force between `600` and `900N`, his tail is safe and the monkeys move together.