# $$k =?$$

A body of mass $$m = 10^{-2} ~ \text{kg}$$ is moving in a medium and experiences a frictional force $$F = -kv^2$$. Its initial speed is $$v_0 = 10 ~ \text{ms}^{-1}$$. If, after $$10 \text{ s}$$, its energy is $$\dfrac{1}{8}mv^2_0,$$. what is the value $$k$$?

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