How long will a fishing line with a coefficient of elasticity of 0.5 kN / m lengthen when a fish weighing 250 g is lifted vertically?

Given: k (stiffness coefficient of the considered fishing line) = 0.5 kN / m (500 N / m); m (mass of fish lifted vertically upwards) = 250 g (0.25 kg).
Constants: g (acceleration due to gravity) = 9.8 m / s2.
The amount of line elongation is determined from the equality: F = k * x = m * g, whence x = m * g / k.
Let’s make the calculation: x = 0.25 * 9.81 / 500 = 0.0049 m (4.9 mm).
Answer: The elongation of the fishing line is 4.9mm.