The $30kg$ block A slides on a rough horizontal surface $)=0\mathrm{.}2,{}_k=(0\mathrm{.}15$ when a $250N$ force is applied to

it as shown. It is connected by an inxtensible cable to a $25kg$ block $B$ which is attached to a spring of constant

$k=2k\frac{N}{m}.$ At the instant shown the system is at rest and the spring is compressed $50mm.$ Determine

$($a$)$ the velocity of block $B$ after block A has moved $30mm(larr).$

$($b$)$ maximum velocity of block $A$

$($c$)$ maximum extension in the spring