Step-by-step explanation:
we are to use the law of momentum
where by total momentum before collision is equal to total momentum after collision hence m1u1+m2u2 =V(M1+M2)
(3200×40)+(2000×30)=V(3200+2000)
128000+60000=V(5200)
188000=5200V
188000÷5200=5200V÷5200
V=36.154m/s