Moment of inertia I of laminar sheet passing through centre of mass and perpendicular to its length is given by,
I = M×L2/12 = 1.2 (given) ......................(1)
we get length L from eqn.(1) as L = 69 cm. Hence Centre of Mass of laminar sheet from AB is 34.5 cm
At first impact at P, speed vi of laminar plate at impact point is given by, vi = ω×0.5 = 1×0.5 = 0.5 m/s
speed vf at impact point after impact at P is obtained from , M(vi - vf) = 6 ..............(2)
LHS of eqn.(2) is change in momentum , which is due to the impulse given to laminar sheet during impact.
we are given that impulse is 6N-s as given in RHS
solving for vf in eqn.(2) using the values of M and vi, we get vf = 0.3 m/s
Now, laminar sheet moving towards Q with initial speed 0.3 m/s at impact point and making second impact and getting bounce back.
speed after second impact at Q is obtained as we did above, because same impulse is given at Q also.
we get the speed at impact point after second impact at Q as 0.1 m/s.
Hence when the laminar sheet is returning to P with angular speed ( ω = v/r) 0.1/0.5 = 0.2 rad/s
When third impact is happening at P, as calculated before, laminar sheet will loose speed 0.2 m/s at impact point.
But before third impact the initial speed itself 0.1 m/s
hence laminar sheet will come to rest at third impact happening at P