Elastic Collisions between two objects

[Flinze]

Homework Statement

You have an inertia of 52 kg and are standing at rest on an iced-over pond in your skates. Suddenly, your 60-kg brother skates in from the right with x component of velocity -4.9 m/s and collides elastically with you.

1. What is the siblings' relative speed after the collision?

Homework Equations

m1v1+m2v2=m1v1+m2v2

The Attempt at a Solution

This is part of my assignment online, and it when I plug in 4.55 m/s it says my answer is incorrect. I'm lost at this point.
Thanks in advance!

 

[ehild]

Homework Statement

You have an inertia of 52 kg and are standing at rest on an iced-over pond in your skates. Suddenly, your 60-kg brother skates in from the right with x component of velocity -4.9 m/s and collides elastically with you.

1. What is the siblings' relative speed after the collision?

Homework Equations

m1v1+m2v2=m1v1+m2v2

Has the above equation any information? It is a trivial identity.

The Attempt at a Solution

This is part of my assignment online, and it when I plug in 4.55 m/s it says my answer is incorrect. I'm lost at this point.
Thanks in advance!

Relative with respect what?
The question is the relative speed of you and your brother after the collision.