consider east-west direction along X-axis and north-south direction along Y-axis
[tex]V_{ra}[/tex] = velocity of migrating robin relative to air = 12 j m/s
(where "j" is unit vector in Y-direction)
[tex]V_{ag}[/tex] = velocity of air relative to ground = 6.3 i m/s
(where "i" is unit vector in X-direction)
[tex]V_{rg}[/tex] = velocity of migrating robin relative to ground = ?
using the equation
[tex]V_{rg}[/tex] = [tex]V_{ra}[/tex] + [tex]V_{ag}[/tex]
[tex]V_{rg}[/tex] = 12 j + 6.3 i
[tex]V_{rg}[/tex] = 6.3 i + 12 j
magnitude : sqrt((6.3)² + (12)²) = 13.6 m/s
direction : tan⁻¹(12/6.3) = 62.3 deg north of east
