Mia walks with a velocity of 1.3 m/s south. She does so while riding on a train that is traveling with a velocity of 4.6 m/s north. What is Mia's velocity?
If you look Mia from inertial frame of reference i.e Earth, you'll see that she's moving with, V = 4.6 - 1.3 = 3.3 m/s. So with respect to ground, she'll be moving at 3.3 m/s toward north.
