question_answer

Consider elastic collision of a particle of mass m moving with a velocity u with another particle of the same mass at rest. After the collision the projectile and the struck particle move in directions making angles \[{{\theta }_{1}}\]and \[{{0}_{2}},\]respectively with the initial direction of motion. The sum of the angles \[{{\theta }_{1}}+{{\theta }_{2}},\] is

A) \[45{}^\circ \]                       

B) \[90{}^\circ \]

C)      \[135{}^\circ \]

D)      \[180{}^\circ \]