Chapter 9, Problem 60P

(III) For an elastic collision between a projectile particle of mass m_A and a target particle (at rest) of mass m_B, show that the scattering angle. ${{\theta }^{\prime }}_{\text{A}}$, of the projectile (a) can take any value, 0 to 180°, for m_A < m_B, but (b) has a maximum angle ϕ given by cos² ϕ = 1 – (m_B/m_A)² for m_A > m_B.