massless spring with force constant

$496$ N$/$m is fastened at its left end to a vertical

wall, as shown below.

The acceleration of gravity is $9\mathrm{.}8$ m$/$s$2.$

$6$ kg $5$ kg

$496$ N$/$m

Initially, the $6$ kg block and $5$ kg block rest

on a horizontal surface with the $6$ kg block in

contact with the spring $($but not compressing

it$)$ and with the $5$ kg block in contact with the

$6$ kg block. The $6$ kg block is then moved to

the left, compressing the spring a distance of

$0\mathrm{.}8$ m$,$ and held in place while the $5$ kg block

remains at rest as shown below.

$6$ kg $5$ kg

k $0\mathrm{.}8$ m

The $6$ kg block is then released and accelerates

to the right, toward the $5$ kg block. The

surface is rough and the coefficient of friction

between each block and the surface is $0\mathrm{.}3.$ The

two blocks collide, stick together, and move

to the right. Remember that the spring is not

attached to the $6$ kg block.

Find the speed of the $6$ kg block just before

it collides with the $5$ kg block.

Answer in units of m$/$s$.$