Two boxes are stacked, box $A$ is placed on a horizontal surface with no friction, box $B$ is placed on box $A$ with unknown coefficient friction between the two. Box $A$ does not slide relative to box $B$, what is the acceleration of both boxes?
We are given the weight of box $A$, $48$ kg, and box $B$, $11$ kg. We are also given the force that is being applied on box $A$, is $149 N$.
The roadblock with this question is how are we supposed to find the acceleration of both boxes if they do not move relative to each other and we are not given the coefficient of friction between the two boxes.