A block of mass $5\text{ kg}$ moves along the floor of a hall with an initial speed of $5\text{ m s}^{-1}$. It strikes an uncompressed spring and compresses it till the block becomes motionless. If the force constant of the spring is $10000\text{ N m}^{-1}$ and the spring is compressed by $5\text{ cm}$, calculate the effective force of kinetic friction.