Chapter 9, Problem 71P

ILW In Fig. 9-21, projectile particle 1 is an alpha particle and target particle 2 is an oxygen nucleus. The alpha particle is scattered at angle θ₁ = 64.0° and the oxygen nucleus recoils with speed 1.20 × 10⁵ m/s and at angle θ₂ = 51.5°. In atomic mass units, the mass of the alpha particle is 4.00 u and the mass of the oxygen nucleus is 16.0 u. What are the (a) final and (b) initial speeds of the alpha particle?

Figure 9-21 An elastic collision between two bodies in which the collision is not head-on. The body with mass m₂ (the target) is initially at rest.