Two block on each other with friction

[Sarah00]

Homework Statement

Homework Equations

F = ma
Ffr = u * Fn

The Attempt at a Solution

After drawing FBD
For m2: we have only friction force in horizontal axis so Ffr = ma ==> u * Fn = ma ==> u * mg = ma ==> u * g = a ==> a = 0.5 * 10 = 5 m/s2
Now, moving to m1:
F - Ffr = ma ==> F - u Fn = 10 * 5 ==> F - 0.5*130 = 50 ==> F - 65 = 50 ==> F = 115 N

But it is not in choices,

Is my solution wrong?
or
Are the choices wrong?

 

[Dr. Courtney]

One of the choices is right. Your solution is wrong.

a = Fnet/m

What mass is needed in this equation?

 

[TSny]

Now, moving to m1:
F - Ffr = ma ==> F - u Fn = 10 * 5 ==> F - 0.5*130 = 50

Did you use the correct value for the normal force here?

 

[Sarah00]

I though that the mistake is with the Fn.
Fn here is the sum of two weights as net vertical force is zero

Dr Courtney, you considered them as single mass I see. The answer will be 65 N then. but I want to know my mistake

 

[TSny]

I though that the mistake is with the Fn.
Fn here is the sum of two weights as net vertical force is zero

Think about whether the friction force acting on m1 is coming from m2 or coming from the ground.

What is the normal force acting between m1 and m2?