1. The problem statement, all variables and given/known data A sphere of mass m is moving with a speed V along a horizontal straight line. It collides with an identical sphere of mass m moving along the same straight line with speed u (u<V). Show that the magnitude of impulse on either sphere is ½m(1+e)(V-u), where e is the coefficient of restitution between the two spheres. 2. Relevant equations m1u1 +m2u2 = m1v1 +m2v2 V2-V1/ u1-u2= e 3. The attempt at a solution I calculated impulse on sphere with velocity V. I =m(V1-V). Using coefficient of restitution, I get I = m(u1-e(V-u)-V). Using equation formed from conservation of momentum, I get I =m[u-V1- e(V-u)]. I have trouble getting rid of the u and V1 terms. How do I go about this?