# Balancing forces application

A plank of mass $$2 \text{ kg}$$ and length $$1 \text{ m}$$ is placed on a horizontal floor. A small block of mass $$1 \text{ kg}$$ is placed on top of the plank, at its right extreme end. The coefficient of friction between plank and floor is $$0.5$$ and that between plank and block is $$0.2$$. If a horizontal force $$=30 \text{ N}$$ starts acting on the plank to the right, the time after which the block will fall off the plank is

Take $$g=10 \text{ m/s}^{2}$$

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