Objects A and B are at the origin. If object A moves to $(-7 ,-5 )$ and object B moves to $(1 ,-1 )$ over $8 s$ , 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 · 2016-06-16T22:06:02

$v_"AB"=sqrt5/2" "m/s$

$v_"BA"=-sqrt5/2" "m/s$

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$"when the object moves from origin to the point of a the position"$ $"of its will have changed"$
$"figure above shows displacement of the object A"$

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$"the figure above shows displacement of the object B"$

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$"the relative displacement of B from perspective of A is shown in "$
$"figure"$

$"the relative displacement may be calculated using Pythagoras or"$
$"cosine laws"$

$Delta s=sqrt((1+7)^2+(-1+5)^2)=sqrt((8)^2+(4)^2)=sqrt(64+16)=sqrt(80)$
$Delta s=sqrt 80=4sqrt5 " "m$

$v_"AB"=(Delta s)/(delta t)$

$v_"AB"=(4sqrt5)/8$

$v_"AB"=sqrt5/2" "m/s$

$v_"BA"=-sqrt5/2" "m/s$

enter image source here

Objects A and B are at the origin. If object A moves to (-7 ,-5 )(-7 ,-5 ) and object B moves to (1 ,-1 )(1 ,-1 ) over 8 s8 s, what is the relative velocity of object B from the perspective of object A? Assume that all units are denominated in meters.