A $50-$cm $330-$cm $320-$cm block weighing $150$ N is

to be moved at a constant velocity of $0\mathrm{.}80$ m$/$s on an inclined

surface with a friction coefficient of $0\mathrm{.}27.($a$)$ Determine

the force F that needs to be applied in the horizontal direc$-$

tion. $($b$)$ If a $0\mathrm{.}40-$mm$-$thick oil film with a dynamic viscos$-$

ity of $0\mathrm{.}012$ Pa$?$s is applied between the block and inclined

surface, determine the percent reduction in the required

force.