d
$F_{\text {net }}=m a=F \cos \theta-m g-\mu F \sin \theta$
$\int_{0}^{0} \mathrm{mdv}=\int_{0}^{\mathrm{t}_{0}}(\mathrm{F} \cos \theta-\mathrm{mg}-\mu \mathrm{F} \sin \theta) \mathrm{dt}$
$\frac{\pi}{2}=\theta_{0} \times t_{0} \& \theta=\theta_{0} \times t$
$\Rightarrow F=\frac{m g \times \pi}{2(1-\mu)}$