# Variable friction Work Done

A block of mass $$2 \text{ kg}$$ and length $$1 \text{ m}$$ is placed on a rough surface (having variable kinetic friction coefficient). A horizontal force $$F$$ is applied such that block moves slowly. If total heat lost in this process is $$\frac{4N}{3}$$ Joule. Find the value of '$$N$$'.

Assume $$g = 10 \text{ m/s}^2$$, ($$\mu_k = x$$ for $$0 \leq x \leq 1$$ & $$\mu_k = 0$$ for $$x \geq 1$$)

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