Objects A and B are at the origin. If object A moves to $(2 ,1 )$ and object B moves to $(5 ,2 )$ over $4 s$ , what is the relative velocity of object B from the perspective of object A?

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Answer 1 · 2017-02-09T14:21:01

$sqrt10/4$ in the direction given by $tan^(-1)(1/3)$

As the displacement for object A is $(2,1)$

and displacement for object B is $(5,2)$

relative displacement of B w.r.t. A is $(5-2,2-1)$ or $(3,1)$

as compared to $(0,0)$ at the start of $4$ seconds

Hence, relative velocity of object B from the perspective of object A is $3/4hati+1/4hatj$

or $sqrt((3/4)^2+(1/4)^2)=sqrt10/4$ in the direction given by $tan^(-1)((1/4)/(3/4))=tan^(-1)(1/3)$

Objects A and B are at the origin. If object A moves to (2 ,1 )(2 ,1 ) and object B moves to (5 ,2 )(5 ,2 ) over 4 s4 s, what is the relative velocity of object B from the perspective of object A?