Relative Velocity
If two objects A and B are moving with velocities and then
is the velocity of B relative to A
That is, is the velocity that B appears to have to an observer moving with A.
Imagine the movement of B from an A-centric point of view. E.g. if B and A are perpendicular and moving at the same rate towards one point, it would appear B relative to A would just be a certain magnitude representing speed moving directly downwards. This is expressed in the equation above.
Practice Question
from sadler
- Ship A is travelling due North at 10km/h.
- Ship B is travelling on a bearing 030deg at 15km/h
- What is the velocity of ship B relative to ship A?