A girl at an airport rolls a ball north on a moving walking that moves east. If the ball's speed with respect to the walkway is 0.15m/s and the walkway moves at a speed of 1.50m/s, what is the velocity of the ball relative to the ground?

We have to add two vectors.

Vector #1: 0.15 m/s north

Vector #2: 1.50 m/s east

Their sum:

Magnitude: √ (0.15² + 1.50²)

Magnitude = √ (0.0225+2.25)

Magnitude = √2.2725

Magnitude = 1.5075 m/s

Direction = arctan (0.15/1.50) north of east

Direction = 5.71° north of east