Objects A and B are at the origin. If object A moves to (6,5) and object B moves to (1,12) 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
Sep 27, 2017

vBA=(53ˆi+173ˆj)ms

Explanation:

A moves Origin (0,0) to (6,5)
Displacement vector of A is
dA=(60)ˆi+(50)ˆj
dA=6ˆi5ˆj
time is 3 sec
Velocity vector of A
vA=dAt=6ˆi5ˆj3=63ˆi53ˆj

B moves Origin (0,0) to (1,12)
Displacement vector of B is
dB=(10)ˆi+(120)ˆj
dB=1ˆi+12ˆj
time is 3 sec
Velocity vector of B
vB=dBt=1ˆi+12ˆj3=13ˆi+123ˆj

Relative Velocity of B from the perspective of A
vBA=vBvA
vBA=1ˆi+12ˆj36ˆi5ˆj3
vBA=1ˆi+12ˆj(6ˆi5ˆj)3
vBA=1ˆi+12ˆj+6ˆi+5ˆj3
vBA=5ˆi+17ˆj3=(53ˆi+173ˆj)(ms)