F = m g \sqrt{{(1 - \frac{l}{L})}^{2} + {(μ \frac{l}{L})}^{2}} \approx 10 N

${F =mg\sqrt{\left(1-{l\over L}\right)^2+\left(\mu{l \over L}\right)^2}\approx 10\mathrm{N}}$

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