$6.\backslash ()^\{-1\}\backslash )$ How large a horizontal force is required to give a $8$ kg block an acceleration of $\backslash (5\backslash$mathrm$\{$~ms$\}^\{-2\}\backslash )$ across a floor if the coefficient of sliding friction between the block and the surface is $0\mathrm{.}25$

b$)$ What weight hanging from a cord attached to this block and passing over a small fricionless pulley will produce this acceleration?

a$)$

b$)$