A person sitting inside an elevator performs a weighing experiment...

A person sitting inside an elevator performs a weighing experiment with an object of mass 50 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 $T=40 \pi \mathrm{~s}$. Taking acceleration due to gravity, $g=10 \mathrm{~m} / \mathrm{s}^2$, the maximum variation of the object's weight (in N ) as observed in the experiment is _______ .