Problem $2$:

The mass of box $\backslash ($ A $\backslash )$ is $30$ kg $,$ and the mass of box $\backslash ($ B $\backslash )$ is $10$ kg $.$ The coefficients of friction between box $\backslash ($ A $\backslash )$ and the ramp are $\backslash (\backslash$mu$=0\mathrm{.}30\backslash$mathrm$\{$~s$\}\backslash )$ and $\backslash (\backslash$mu$=0\mathrm{.}28\backslash ).$ k Can the boxes remain in equilibrium in the positions shown? If so$,$ what is the magnitude of the friction force exerted on box $\backslash ($ A $\backslash )$ by the ramp?

Solution: