Use the Picture to the Right to Answer the Next $\alpha$

Multiple Choice

Use the picture to the right to answer the next question. A puck of m₁ and moving with velocity v₁ collides elastically with a second puck of mass m₂, which is initially at rest. After the collision, m₁ moves with velocity v₁’ at an angle α below the x axis and m₂ moves with velocity v₂’ at an angle θ above the x axis.

-The conservation of momentum along the x direction can be written as

A) m₁ v₁ = m₁v₁' cos $\alpha$ + m₂v₂' cos $\theta$
B) 0 = m₁v₁' cos $\alpha$ + m₂v₂' cos $\theta$
C) m₁ v₁ = m₁v₁' sin $\alpha$ + m₂v₂' sin $\theta$
D) 0 = m₁v₁' sin $\alpha$ + m₂v₂' sin $\theta$
E) none of the above