The horizontal force P$=79$N is applied to the upper block with the system initially stationary. The block masses are m$\_($A$)=19$kg and m$\_($B$)$

$=8$kg$.$ Determine the magnitudes of the frictions forces F$\_(1)$A and the groundF$\_(2)$A and B $\backslash$mu $\_(1)=0\mathrm{.}37,\backslash$mu $\_(2)=0\mathrm{.}53$ and $($b$)\backslash$mu $\_(1)=0\mathrm{.}24,\backslash$mu $\_(2)=0\mathrm{.}65.$ Assume that the

coefficients of kinetic friction are $70$ percent of the static values.

Answers:

$($a$)$ F$\_(1)=$

N F$\_(2)=$

i

N

$($b$)$ F$\_(1)=$

N$,$F$\_(2)=$

i

N