Question

Objects A and B are at the origin. If object A moves to `(-8 ,-2 )` and object B moves to `(-5 ,-4 )` 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.

Answer 1

Object B moves away from object A with a speed of `1.202` `m/sec` in a direction given by `-33.7^o` relative to `x` axis.

Explanation:

As object A moves to `(-8,-2)` and object B moes to `(-5,-4)`, the distance between them after `3` seconds is

`sqrt((-5-(-8))^2+(-4-(-2))^2)` i.e. `sqrt(3^2+(-2)^2)` or

`sqrt(9+4)=sqrt13=3.606`

Hence object B moves away from object A with a speed of `3.606/3=1.202` `m/sec`.

Direction is given by `tan^-1((-4-(-2))/(-5-(-8)))=tan^-1(-2/3)=-33.7^o` relative to `x` axis