Two particles `A` and `B` are situated at a distance `d = 2m` apart. Particle `A` has a velocity of `10 m//s` at an angle of `60^@` and particle `B` has a velocity `v` at an angle `30^@` as shown in figure. The distance `d` between `A` and `B` is constant. the angular velocity of `B` with respect to `A` is :
.