In this first we apply conservation of momentum,
M1V1=M2V2
(40/1000)kg * 430 m/s = 4.8 kg * V2
V2= 3.6 m/s.
Now applying conservation of energy,
Increase in potential energy of pendulum= decrease in kinetic energy
gh=(1/2)v^2
9.8 H = (1/2) * 12.96
H= 0.661~ 0.66 m