Answer:
vB = 8.57[m/s]
Explanation:
Since there is no external force that generates momentum, the amount of momentum is conserved so you will have the following equation
[tex]m_{A}*v_{A}=m_{B}*v_{B}\\Where:\\m_{A}= 90[kg]\\v_{A}=10[m/s]\\m_{B}=105[kg]\\\\Therefore:\\\\v_{B}=\frac{m_{A}*v_{A}}{m_{B}}\\ v_{B}=\frac{90*10}{105}\\v_{B}=8.57[m/s][/tex]
