A car travelling 110 km/h [S25°W] turns to a heading of [S25°E]. What is the car's change in velocity ?
Change in V. = 110km/h[S25oE] - 110km/h[S25oW].
X = 110*Cos25 - (-110*Cos25) = 199.4 m/s.
Y = -110*sin25 - (-110*sin25) = 0.
Change in V. = X = 199.4 m/s.
The above angles are referenced to
the y-axis.
If the angles were referenced to the
x-axis: X = 93 m/s, Y = 0.
The angles would be 65o instead of 25o.