Need help calculating the tension in the string of two boxes with friction

[jami8337]

Homework Statement

Two boxes are connected by a cord running over a pulley. Box A sits on a table and has a mass of 5.0 kg while box B hangs
freely and has a mass of 2.0 kg. Box A moves to the right and box B moves
downwards. If the coefficient of kinetic friction between box A and the table is
0.20, what is the acceleration of the system and the tension in the cord? You
may assume that the cord remains taut and does not stretch.

Homework Equations

F=ma
fk=mu*Fn

The Attempt at a Solution

The first part is fine i get 1.4m/s2

then the second part to calculate tension I am lost with what to do:

m1g-T=m1a
T-fk=m2a

where m1= 5kg
m2= 2kg

the answer is supposed to be 17N but when i solve for T i don't get anywhere near that...

thanks

 

[PhanthomJay]

You got your m1 and m2 reversed.