Solving a Static and Kinetic Friction Problem

[lessey]

Homework Statement

In the following figure(one box on a table, m1, connected to a string that is on a pulley attached to box m2), m1=10kg and m2=4kg. The coefficient of static friction between m1 and the horizonatl surface is 0.50 while the coefficient of kinetic friction is 0.30. (a) If the system is released from rest, what will its acceleration be? (b) If the system is set in motion with m2 moving downward, what will be the acceleration of the system?

Homework Equations

Fnet=ma

The Attempt at a Solution

I've only done problems with a single friction or coefficient of friction given and I don't understand how to use kinetic or static. I've never worked with them before so I have no idea on how to go about this.

 

[JHamm]

The static coefficient is used to calculate the force of friction when there is no motion, if things are moving you use the kinetic coefficient to calculate friction. For part (a) what are all the forces on the two boxes?