posted by Scott on .
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 è'2 = 45° from the neutron's initial direction. The neutron's initial speed is 6.6x10^5 m/s. Determine the angle at which the neutron rebounds, è'1, measured from its initial direction.
What is the speed of the neutron after the collision?
What is the speed of the helium nucleus after the collision?
Elastic? Ok, momentum equations and energy equations can be used.
The sum of the final KE =initial KE
The sum of momentums in orig direction=momentum of neutron originally.
The sum of momentum in direction perpendicular to orig direction=zero
You will have three unknowns:
velocity of neutron after
velocity of He after
Three equations, three unknowns. A little algebra and trig :)
thanks but I know that there are three unknowns and three equations. Getting the formulas are the difficult part.