Newton's Laws and coefficient of static friction

[jehan4141]

A 5.00-kg block is placed on top of a 12.0-kg block that rests on a frictionless table. The coefficient of static friction between the two blocks is 0.600. What is the maximum horizontal force that can be applied before the 5.00-kg block begins to slip relative to the 12.0-kg block, if the force is applied to (a) the more massive block and (b) the less massive block?

In this problem does the force of friction have the same magnitude in both A and B? My logic is that it is only the normal force of the small mass that cause the friction in both cases. Is this correct?

 

[PeterO]

A 5.00-kg block is placed on top of a 12.0-kg block that rests on a frictionless table. The coefficient of static friction between the two blocks is 0.600. What is the maximum horizontal force that can be applied before the 5.00-kg block begins to slip relative to the 12.0-kg block, if the force is applied to (a) the more massive block and (b) the less massive block?

In this problem does the force of friction have the same magnitude in both A and B? My logic is that it is only the normal force of the small mass that cause the friction in both cases. Is this correct?

Your assertion about normal force seems sound.