A $20\mathrm{.}0-kg$ box initially at rest is released from the top of an incline that is $10\mathrm{.}0m$ long and makes an angle of $50$ to the horizontal. The incline is adhesive and and thus impedes the motion of the box. If the kinetic friction coefficient of the incline surface is ${}_k=0\mathrm{.}10,$ determine

$($a$)$ the acceleration of the box.

$($b$)$ the box's speed as it reaches the bottom of the incline

$($c$)$ the box's speed as it reaches the bottom of the incline if the incline is frictionless. Explain the difference in your finding as compared to your answer in $2($b$).$