Objects A and B are at the origin. If object A moves to $(- 7, 5)$ $(-7 ,5 )$ and object B moves to $(- 5, - 2)$ $(-5 ,-2 )$ over $2 s$ $2 s$ , what is the relative velocity of object B from the perspective of object A? Assume that all units are denominated in meters.

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Answer 1 · 2017-12-03T13:30:43

$vecv_{Ag} =(-7/2, 5/2);\qquad vecv_{Bg} = (-5/2, -1);$

$vecv_{BA} = vecv_{Bg} + vecv_{gA} = vecv_{Bg} - vecv_{Ag} = (1, 7/2);$

Velocity of A relative to ground:
$vecv_{Ag} = (\Deltavecr_A)/(\Deltat) = ((-7,5)-(0,0))/2=(-7/2, 5/2);$

Velocity of B relative to ground:
$vecv_{Bg} = (\Deltavecr_B)/(\Deltat) = ((-5-2)- (0,0))/2=(-5/2, -1);$

Velocity of B relative to A:
$vecv_{BA} = vecv_{Bg} + vecv_{gA} = vecv_{Bg} - vecv_{Ag};$

$vecv_{BA} = (-5/2, -1)-(-7/2,5/2) = (1, 7/2);$

Objects A and B are at the origin. If object A moves to (-7 ,5 )(−7,5)(-7 ,5 ) and object B moves to (-5 ,-2 )(−5,−2)(-5 ,-2 ) over 2 s2s2 s, what is the relative velocity of object B from the perspective of object A? Assume that all units are denominated in meters.