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## Homework Statement

A pendulum of mass m_1 is released at an angle theta_1 and strikes the pendulum of mass m_2, which rises to angle theta_2. The coefficient of restitution e for the two masses is given. Derive an expression for the angle theta_2.

## Homework Equations

KE_1+PE_1=KE_2+PE_2

e=(v

_{2}'-v

_{1}')/(v

_{1}-v

_{2})

## The Attempt at a Solution

Solving for v

_{1}at time of impact using conservation of energy I get v

_{1}=Sqrt(2gl(1-cos(theta_1)))

I solve the same equation for v'

_{2}=sqrt(2gl(1-cos(theta_2)))

I then plug in the coefficient of restitution equation and solve for theta_2

theta_2= arccos(1-((e*Sqrt(2gl(1-cos(theta_1)))+v'

_{1})^2)/2gl

My issue is determining whether or not this is a complete elastic collision. If so I assume the v'

_{1}would be omitted, correct?