Objects A and B are at the origin. If object A moves to #(5, -1)# and object B moves to #(-7, 8)# 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.

1 Answer
David G.
Mar 9, 2016

This one seems tougher than it really is. The two objects start together at a separation of #0# #m#, and end at a separation of #r=15# #m#, #3# #s# later. That means the relative velocity, #v=(Delta d)/(Delta t)=15/3=5# #ms^-1#.

Explanation:

To find the distance between the final positions of the objects:

#r=sqrt((x_2-x_1)^2+(y_2-y_1)^2)=sqrt((-7-5)^2+(8-(-1))^2)=sqrt(144+81)=15# #m#

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