1. The problem statement, all variables and given/known data A neutron collides elastically with a helium nucleus (at rest initially) whose mass is four times that of the neutron. The helium nucleus is observed to rebound at an angle θ'2 = 41° from the neutron's initial direction. The neutron's initial speed is 6.2 x10^5 m/s. Determine the angle at which the neutron rebounds, θ'1, measured from its initial direction. __° What is the speed of the neutron after the collision? _____m/s What is the speed of the helium nucleus after the collision? _____m/s 2. Relevant equations conservation of momentum conservation of energy 3. The attempt at a solution Wound up with a very messy system of equations involving conservation of momentum in both the x and y directions as well as conservation of energy. Any help would be greatly appreciated!