What Happens to the Box's Velocity on a Rough Surface?

[odie]

a box of mass 12-kg slides at a speed of 10m/s across a smooth level floor, where it enters a rough portion 3 m in length. in the rough portion, the box experiences a horizontal frictional force of 72N.

a) How much work is done by the frictional force?
b) what is the velocity of the box when it leaves the rough surface?
c) what length of rough surface brings the box completely to rest?

thats all, don't ask for more cause there is nothing more to add

 

[rock.freak667]

What did you try?

 

[odie]

well i found out that we have to use W=(F)(d) (still not sure)
but i have no ideas in how to solve b) and c)