In order to calculate the final speed of both blocks together, we can use the equation for conservation of momentum:
Where m3 in this case is the sum of m1 and m2.
So, using m1 = 6, m2 = 5, m3 = 11, v1 = 3.14282 and v2 = 0, let's calculate v3:
Therefore the correct option is number 6.