Finding coefficient of kinetic friction from a speed-time graph

[rgold]

Homework Statement

A 4.30 kg block is pushed along a floor by a constant applied force that is horizontal and has a magnitude of 43.0 N. The figure gives the block's speed v versus time t as the block moves along an x axis on the floor. The scale of the figure's vertical axis is set by vs = 5.30 m/s. What is the coefficient of kinetic friction between the block and the floor?
http://edugen.wileyplus.com/edugen/courses/crs7165/art/qb/qu/c06/pict_6_27.gif

Homework Equations

f=ma

The Attempt at a Solution

i think the acceleration is 5.3 m/s^2 but I am not sure and i don't know where to go once i find the acceleration

 

[rgold]

this is figure