Explanation :
Let the mass of the titanic is [tex]m[/tex].
so, mass of an iceberg is [tex]\dfrac{m}{2}[/tex]
Before collision,
Iceberg is at rest, [tex]u_i=0[/tex]
initial speed of titanic, [tex]u_t=22\ Knots[/tex]
After collision,
Final speed of titanic is, [tex]v_t=6\ Knots[/tex]
Final speed of iceberg is, [tex]v_i=?[/tex]
since, it is a elastic collision. So, the momentum remains conserved.
[tex]m_tu_t+m_iu_i= m_tv_t+m_iv_i[/tex]
[tex]m\times 22+0=m\times6+\dfrac{m}{2}\times v_i[/tex]
so, [tex]v_i=32\ knots[/tex]
Hence, after collision the iceberg will move with velocity of 32 Knots.