Question:
A boy of mass $4 \mathrm{~kg}$ is standing on a piece of wood having mass $5 \mathrm{~kg}$. If the coefficient of friction between the wood and the floor is $0.5$, the maximum force that the boy can exert on the rope so that the piece of wood does not move from its place is N.(Round off to the Nearest Integer)
$\left[\right.$ Take $\left.g=10 \mathrm{~ms}^{-2}\right]$
Solution:
$\mathrm{N}+\mathrm{T}=90$
$\mathrm{~T}=\mu \mathrm{N}=0.5(90-\mathrm{T})$
$1.5 \mathrm{~T}=45$
$\mathrm{~T}=30$