Solving 2 Blocks on a Slope: Find fmax Needed

[shashlik]

Homework Statement

hey I need help with this question I have this sketch and the tell me that m1= 2 kg, m2= 5 kg the say that we don't have friction between m2 and the floor the kinetic friction between m1 and m2 is 0.2 and the static friction is 0.5 and we have the f - f pushing m1

Homework Equations

what fmax need to be that m2 and m1 will stay together and don't fall

 

[haruspex]

and don't fall

So what does that imply regarding your acceleration variable, a?

 

[shashlik]

So what does that imply regarding your acceleration variable, a?

its change
actually, I think I solved it but at the answer, that get 11.2 and I got 11.18
can i uploud and you check if i solved it correctly ?

 

[haruspex]

its change
actually, I think I solved it but at the answer, that get 11.2 and I got 11.18
can i uploud and you check if i solved it correctly ?

Typically an angle of 37 degrees is specified when the author intends a 3-4-5 triangle. Taking cos of it to be exactly .8, and using 10m/s$^2$ for g, gives 11.2N exactly.