Two solid sphres of density `rho` each and R and 2R are hung from a spring and a thread as shown if the thread is burnt.

Options

A. The initial acceleration of lower sphere is zero
B. The initial acceleration of upper sphere is `9 g darr`
C. The initial acceleration of upper sphere is `3 g darr`
D. The initial acceleration of lower sphere is `g darr`

Answer

AB

Explanation

Mass of upper spheres `=rxx4/3 piR^(3)=m`
Mass of lower sphere =`rxx4/3 pi6R^(3) =8m`
at equation kx=8 mg
when string is brunt force in spring will into change.
`a_("upper sphere")=(8 mg+mg)/m=9 g darr`
`a_("lower sphere")=0` as force in spring doesn't change instantaneously.