Objects A and B are at the origin. If object A moves to (5,1) and object B moves to (8,1) over 3s, what is the relative velocity of object B from the perspective of object A? Assume that all units are denominated in meters.

1 Answer
Apr 26, 2016

Treating the positive X-axis as North,
XXXapproximately 4.38msec at 8.75N of W

Explanation:

The distance between points A and B has increased from 0 meters to
XXX(5(8))2+(1(1))2=17313.15 meters
for an average speed of
XXX173m3sec4.38msec

Relative to A, B has moved 13 meters East and 2 meters North.
If θ is the angle North of due East for B's movement relative to A then
XXXtan(θ)=213

XXXθ=arctan(213)8.75

(Remember that velocity must always include a direction as well as a speed).