Understanding Elastic Collisions: Solving a Head-On Collision Problem

[cybernerd]

Homework Statement

A 6 gram ball moving north at a rate of 3 m/s collides head on with an identical ball moving south at 2.0 m/s. The collision is elastic and the first ball moves south at 1 m/s. What is the velocity of the second ball?

Homework Equations

Law of conservation of momentum.
p=mv

The Attempt at a Solution

The question makes no sense to me. According to my solution guide, the other ball moves off at 2.0 m/s. But of the collision is elastic, then no energy should be wasted. So...2.0m/s worth of energy from the first ball is sucked into an abyss? Can anyone shed light on this?

 

[Nabeshin]

Yeah I don't know about this one. Energy's definitely not conserved using the given data. Chalk it up to a miswording?

 

[cybernerd]

I hope so, or we're getting into magic rather than physics...thanks for confirming this...