A person sitting inside an elevator performs a weighing experiment with an object of mass $ 50 \, \text{kg} $. Suppose that the variation of the height $ y $ (in m) of the elevator, from the ground, with time $ t $ (in s) is given by
$$
y = 8\left[1 + \sin\left(\frac{2\pi t}{T}\right)\right],
$$
where $ T = 40\pi \, \text{s} $. Taking acceleration due to gravity, $ g = 10 \, \text{m/s}^2 $, the maximum variation of the object's weight (in N) as observed in the experiment is ____.