A Heavy Object Having Mass $m _ { a }$ Is Attached to a Massless Cord

Multiple Choice

A heavy object having mass $m _ { a }$ is attached to a massless cord. The cord is wrapped around a massless pulley, and the other end of the cord is attached to a lighter object having mass $m _ { b } \left( m _ { a } > m _ { b } \right)$ . The two masses are released. Find the acceleration of the masses.

A) $2 g m _ { b } / \left( m _ { a } + 2 m _ { b } \right)$
B) $2 g m _ { a } / \left( m _ { a } + m _ { b } \right)$
C) $g \times \left( m _ { b } - m _ { a } \right) / \left( 2 m _ { a } + m _ { b } \right)$
D) $g \times \left( m _ { a } - m _ { b } \right) / \left( m _ { a } + m _ { b } \right)$