A thin uniform rod of mass m and length l is free to rotate about its upper end. When it is at rest, it receives an impulse J at its lowest point, normal to its length. Immediately after impact,
A. the angular momentum of the rod is Jl
B. the angular velocity of the rod is 3J/ml
C. the kinetic energy of the rod is `3J^(2)//2m`
D. the linear velocity of the midpoint of the rod is `3J//2m`
