# Elastic Collisions in One Dimension

#### G-reg

1. Homework Statement
A cart with mass 310 g moving on a frictionless linear air track at an initial speed of 1.4 m/s undergoes an elastic collision with an initially stationary cart of unknown mass. After the collision, the first cart continues in its original direction at 0.64 m/s.

2. Homework Equations

(1/2)m1vo^2 +(1/2)m2vo^2 = (1/2)m1vf^2 + (1/2)m2vf^2

3. The Attempt at a Solution

(310)(1.4)^2 + 0 = (310)(.64)^2 + m2vf^2

(310)(1.4)^2 - (310)(.64)^2 = m2vf^2

but I feel like I need vf to find m2 so how am I supposed to go from here?

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#### ideasrule

Homework Helper
Two things have to be conserved in an elastic collision. One is energy, which you have. What's the other one?

#### G-reg

And momentum
which would be

m1v1o = m1v1f + m2v2f ???

#### roflol

you sure it didnt say "inelastic" instead? and what exactly are they asking you to work out : /

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