Take into account that after the impact, the two objects move stick together.
Then, by using the law of conservation of total momentum, you can write the following equation:
Solve the previous equation for v, replace the values of the other parameters and simplify:
![\begin{gathered} v=(m_1v_(1o)+m_2v_(2o))/(m_1+m_2)=\frac{(10.00kg)(2.00(m)/(s))+(10.00kg)(0.00(m)/(s))}{10.00\operatorname{kg}+10.00\operatorname{kg}} \\ v=1.00(m)/(s) \end{gathered}]()
Now, consider that the speed v is the final speed of both objects, that is,
v = v1f = v2f
Hence, you can conclude that v1f = 1.00m/s