QP11

Upon an inclined plane of angle is placed a block of mass m₂. Upon m₂ is placed another block of mass m₁.
The coefficient of static friction between m₂ and the inclined plane is µ_2s and the coefficient of sliding friction is µ_2k.
Likewise, the coefficient of static friction between m₁ and m₂ is µ_1s and the coefficient of sliding friction is µ_1k.
A force F upward and parallel to the plane is applied to m2.

(2 points) (a) What is the acceleration of m₂ when m₁ just starts to slip on it?

(2 points) (b) What is the maximum value of F before this slipping takes place?