Objects A and B are at the origin. If object A moves to (3,8) and object B moves to (2,1) 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
Oct 1, 2017

vBA=ˆi+7ˆj3(ms)

Explanation:

A moves (0,0) to (3,8) in 3 seconds
Displacement OA=(30)ˆi+(80)ˆj=3ˆi8ˆj
Velocity of A vA=displacementtime
vA=3ˆi8ˆj3

B moves (0,0) to (2,1) in 3 seconds
Displacement OB=(20)ˆi+(10)ˆj=2ˆi1ˆj
Velocity of B BA=displacementtime
vB=2ˆi1ˆj3

Velocity of B from perspective of A
vBA=vBvA=2ˆi1ˆj3(3ˆi8ˆj3)
vBA=2ˆi1ˆj+3ˆi+8ˆj3=ˆi+7ˆj3(ms)