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?

1 Answer
Feb 9, 2017

Answer:

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

Explanation:

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)#