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 move off at an angle -45" The neutron's initial speed is 3.9-105 m/s Y Part A Determine the angle of the neutron, ,, after the collision Express your answer using two significant figures. 195) 4. Submit Part B Request Answer Submit C? Determine the speeds of the two particles, and after the collision Express your answers using two significant figures. Enter your answers numerically separated by a comma. 195] 4 Request Answer below the initial direction of the neutron A ? m/s