Objects A and B are at the origin. If object A moves to (-3 ,-8 ) and object B moves to (-2 ,-1 ) over 3 s, what is the relative velocity of object B from the perspective of object A? Assume that all units are denominated in meters.

1 Answer
Pankaj Solanki
Oct 1, 2017

vecv_(BA)=(hati+7hatj)/3 (m/s)

Explanation:

A moves (0,0) to (-3,-8) in 3 seconds
Displacement OA=(-3-0)hati+(-8-0)hatj=-3hati-8hatj
Velocity of A vecv_A="displacement"/"time"
vecv_A=(-3hati-8hatj)/3

B moves (0,0) to (-2,-1) in 3 seconds
Displacement OB=(-2-0)hati+(-1-0)hatj=-2hati-1hatj
Velocity of B vecB_A="displacement"/"time"
vecv_B=(-2hati-1hatj)/3

Velocity of B from perspective of A
vecv_(BA)=vecv_B-vecv_A=(-2hati-1hatj)/3-((-3hati-8hatj)/3)
vecv_(BA)=(-2hati-1hatj+3hati+8hatj)/3=(hati+7hatj)/3 (m/s)

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