A uniform disc of mass m and radius R is free to rotate about its fixed horizontal axis without friction. There is sufficient friction between the inextensible light string and disc to prevent slipping of string over disc. At the shown instant extension in light spring is `(3 mg)/K`, where m is mass of block, g is acceleration due to gravity and K is spring constant. Then select the correct alternative(s).

Options

A. Acceleration of block just after it is released is `(4g)/3`
B. Tension in the string continuously increases till extension in the spring reaches maximum value.
C. Acceleration of the block just after releases `3/4 g`
D. Angular acceleration of disc just after release is `(4g)/(3R)`

Explanation

For disc, from torque equation
`3 mg R-TR=(mR^(2))/2 alpha.....(1)`
By application of Newton's second law on block we get,
`T-mg=ma.....(2)`
where `a=Ralpha....(3)`
solving `a=(4g)/3`