Answer:
12.5 m/s
Step-by-step explanation:
By conservation of momentum, we have that:
![\displaystyle m_1v_1 + m_2v_2 = m_1v_1' + m_2v_2'](https://img.qammunity.org/2023/formulas/physics/high-school/eu9q44c4o55khktlsm796dkqatdphuwmu7.png)
Because the two objects combine after collision, they will have the same velocity:
![\displaystyle m_1v_1 + m_2v_2 = (m_1+m_2)v_f](https://img.qammunity.org/2023/formulas/physics/high-school/ehh4m2pfdi48g6dyvvpfdpjgq8ow4bn6a7.png)
Substitute and solve for final velocity:
![\displaystyle \begin{aligned} (50 \text{ kg})(15\text{ m/s}) + (50\text{ kg})(10\text{ m/s}) & = ((50+50)\text{ kg})v_f \\ \\ v_f & = 12.5\text{ m/s}\end{aligned}](https://img.qammunity.org/2023/formulas/physics/high-school/wlrdzz4jhkbsffhzgkfqnde3jvywyiwn2m.png)
In conclusion, the final velocity of the system will be 12.5 m/s.