A uniform rod of mass `m` and length `l` is placed over a smooth horizontal surface along the `y`-axis and is at rest as shown in Fig. An impulsive force `F` is applied for a small time `/_\t` along `x`-direction at point `A`. The `x`-coordinate of end `A` of the rod when the rod becomes parallel to `x`-axis for the first time is [initially, the coordinate of centre of mass of the rod is `(0, 0)`]