The figure shows that particle \( A \) is projected from point \( P \) with velocity \( u \) alo...

The figure shows that particle \( A \) is projected from point \( P \) with velocity \( u \) along the plane and simultaneously another particle \( B \) with velocity \( v \) at an angle \( \alpha \) with vertical. The particles collide at point \( Q \) on the plane. Then
(1) \( v \sin \left(\alpha-\theta_{0}\right)=u \)
(2) \( v \cos \left(\alpha-\theta_{0}\right)=u \)
(3) \( v=u \)
(4) None of these