(Mass of truck) (velocity of truck) = (mass of kitten) (horizontal component of kitten's momentum)

(Mass of kitten) (horizontal component of kitten's momentum) = (mass of truck) (velocity of truck)

(0.6 kg) (horizontal component of kitten's momentum) = (1.2 kg) (4 m/s)

horizontal component of kitten's momentum = (1.2 kg) (4 m/s) / 0.6 kg

horizontal component of kitten's momentum = 8 m/s

If V is the total speed of the kitten then, Vcos30'=8m/s

So, V = 16/sqrt(3) m/s.