Aplane travels 350 km south along a straight path with an average velocity of 125 km/h to the south. the plane has a 30 minute layover, and then travels 220 km south with an average velocity of 115 km/h to the south. what is the average velocity for the trip? . a.120 km/hr to the south. b.110 km/hr to the south. c. 121 km/hr to the south. d. need more information

Average Velocity = Total Displacement / Total time

1st part of journey,  350 km at velocity 125 km/h

Time = 350 / 125 = 2.8 hours.

2nd part of journey,  220 km at velocity 115 km/h

Time = 220 / 115 = 1.9 hours

Average Velocity = Total Displacement / Total time

                               = (350 + 220) / (2.8 + 1.9)

                                =   570 / 4.7  ≈ 121.3 km/hr

Average Velocity ≈ 121 km/hr due south. 

Option C.