Here it is given that speed of migrating Robin is 12 m/s relative to air
so we can say that
[tex]\vec v_{ra} = 12 m/s[/tex] North
so it will be
Let North direction is along Y axis and East direction is along X axis
[tex]\vec v_{ra} = 12\hat j[/tex]
also it is given that speed of air is 6.7 m/s relative to ground
[tex]\vec v_a = 6.7 \hat i[/tex]
now as we know by the concept of relative motion
[tex]\vec v_{ab} = \vec v_a - \vec v_b[/tex]
[tex]\vec v_{ra} = \vec v_r - \vec v_a[/tex]
now by rearranging the terms
[tex]\vec v_r = \vec v_{ra} + \vec v_a[/tex]
[tex]\vec v_r = 12 \hat j + 6.7 \hat i[/tex]
now we need to find the speed of Robin which means we need to find the magnitude of its velocity which we found above
So here we will say
[tex]v_r = \sqrt{12^2 + 6.7^2}[/tex]
[tex]v_r = 13.7 m/s[/tex]
so the net speed of Robin with respect to ground will be 13.7 m/s
