By Ivan Erofeev
A small brick is squeezed between two parallel planes in zero-gravity. The planes are perpendicular to the axis z. The lower plane always stays in rest, whilst the upper one is moving with the constant velocity \vec v along the axis x, see the figure. Initially the velocity of the brick \vec u_0 is perpendicular to \vec v and lies in axis y. The friction between the planes and the brick is dry with the same coefficient of kinetic friction. Given the initial acceleration of the brick a_0, find the displacement l_y of the brick along the axis y after a long time. Obtain an expression of l_y for arbitrary speeds v and u_0, and evaluate the answer for v=u_0=1 m/s, and a_0=1 m/s2 with four digits.
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