Question Difficulty

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 scatter at an angle $\backslash$theta $\_(2)=51\backslash$deg from

the neutron's initial direction. The neutron's initial speed is $68000*($m$)/($s$).$ Determine the angle at which the neutron scatters, $\backslash$theta $\_(1),$ 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$)$