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 $\underline{\hspace{2cm}}$.