True
The momentum is always conserved in a collision.
momentum (p) = mass (m) x velocity (v)
conservation of momentum:
m1 v1 + m2 v2 = (m1 + m2) vf
Where:
m1 = mass1
m2= mass 2
v1= initial velocity of mass one
v2 = initial velocity of mass two = 0 m/s ( rest)
Vf = final velocity of the two balls stuck together.
m1 v1 = (m1+m2) vf
m1 v1 = 0
Since m1 and v1 are not zero the momentum is not conserved.