Question

A child weighing $25\text{kg}$ slides down the rope hanging from a branch of a tall tree. If force of friction acting against him is $200\text{N}$, the acceleration of child is (take $g=10{\text{m/s}}^2$ )

• A. $22.5{\text{m/s}}^2$
• B. $8{\text{m/s}}^2$
• C. $5{\text{m/s}}^2$
• D. $2{\text{m/s}}^2$

Answer 1

The correct option is D $2{\text{m/s}}^2$

By the newtons equation, $F_{net}=m{a}_{net}$,

Force on the child will have, frictional force upward and his own weight donwward and the boy will be moving down with acceleration $\left(a\right)$ let say.

Writing the force equation we get,
$mg-f_k=ma$
$\Rightarrow 250-200=25a$, as the mass of the child is $25\text{kg}$

By solving we get,
$a=2{\text{m/s}}^2$

Hence option D is the correct answer.