Question

The monkey $B$ shown in figure is holding on to the tail of the monkey $A$ which is climbing up a rope. The masses of the monkeys $A$ and $B$ are $5kg$ and $2kg$ respectively. If $A$ can tolerate a tension of $30N$ in its tail, what force should it apply on the rope in order to carry the monkey $B$ with it? (Take $g=10m{s}^{-2}$ )

• A. 105 N
• B. 108 N
• C. 10.5 N
• D. 100 N

Answer 1

Answer: (A)

If $A$ is climbing with constant velocity, then
$T^{{}^{\prime }}=5g+T$ and $T=2g$
$T^{{}^{\prime }}=5g+2g=7g$
Suppose $A$ is climbing with acceleration a such that $T=30N$
$T-2a=2a$
$30-2\times 10=2a$

or $a=5m{s}^{-2}$
Again, $T^{{}^{\prime }}-T-5g=5a$
Or $T^{{}^{\prime }}=T+5g+5a$
Or $T^{{}^{\prime }}=(30+50+25)N$
$=105N$