Physics - Kinematics Question with Solution | TestHub

A man throws a ball of mass$m$from a moving plank ($\mathrm{A}$). The ball has a horizontal component of velocity$u=3\sqrt{34} \mathrm{m} {\mathrm{s}}^{-1}$with respect to ground towards another man standing on stationary plank ($\mathrm{B}$), as shown in the figure. The combined mass of plank$\mathrm{A}$with man as well as that of plank$\mathrm{B}$with the other man is$2m$each. the x-y plane represents the horizontal plane which is frictionless. If initially, plank$\mathrm{A}$was moving with speed$u\hat{\mathrm{i}}$with respect to ground, then the relative velocity of plank$\mathrm{B}$(in$\mathrm{m} {\mathrm{s}}^{-1}$) with respect to plank$\mathrm{A}$(after the man on plank$\mathrm{B}$catches the ball) minus$10 \mathrm{m} {\mathrm{s}}^{-1}$is