Q. A mass of $10\, kg$ is suspended by a rope of length $4\, m$, from the ceiling. A force $F$ is applied horizontal!)' at the mid-point of the rope such that the top half of the rope makes an angle of $45^°$ with the vertical. Then $F$ equals: (Take $g = 10\, ms^{-2}$ and the rope to be massless)
Solution:
For equilibrium,
$T \,sin \,45^{\circ} = F \quad....\left(1\right)$
and $T \,cos \,45^{\circ } = 10g \quad ....\left(2\right)$
equation $\left(1\right)/\left(2\right)$
we get $F = 10g$
$= 100 \,N$
