Two objects of masses m and 2m are connected by a massless string passing over a fixed smooth pulley. The acceleration of heavier mass wrt to lighter ones is?? pls its urgent....

1.8g/3

2. 4g/3

3. 2g/3

4. 0

When two masses are connected with pulley.
If heavier mass is going downward with an acceleration a then lighter mass will also go upward with same acceleration, but force on heavier mass and lighter mass would be different as masses are different.
$$\begin{gathered} For the lower mass , net force is in downward direction \\ {f}_1 = 2mg-T \\ 2ma = 2mg-T--\left(1\right) \\ net force on lighter mass is in upward direction. \\ {f}_2 = T-mg \\ ma = T-mg--\left(2\right) \\ on solving these two equations we get \\ a = \frac{g}{3} \\ this is same for both the masses. \end{gathered}$$