A Puck with a Mass $m _ { 1 } = 50 \mathrm {~g}$

Multiple Choice

A puck with a mass $m _ { 1 } = 50 \mathrm {~g}$ moving at 1.0 m/s approaches a stationary puck with a mass $m _ { 2 } =$
100 g on a frictionless air table, and they undergo a sudden two-dimensional elastic collision. After
the collision, both pucks have identical speeds, but travel in different directions. What is the angle
between the original and final paths of puck with mass $m _ { 1 } ?$

A) $150 ^ { \circ }$
B) $30 ^ { \circ }$
C) $90 ^ { \circ }$
D) $60 ^ { \circ }$
E) $120 ^ { \circ }$