What is the work done by friction?

[snash1057]

A flight attendant pulls her 70.0 N flight bag a distance of 269 m along a level airport floor at a constant speed. The force she exerts is 32.0 N at an angle of 52.0° above the horizontal.


(a) Find the work she does on the flight bag.


_5299_J
(b) Find the work done by the force of friction on the flight bag.


____J
(c) Find the coefficient of kinetic friction between the flight bag and the floor.

_____


i found (a) by using W=fdCos, 32.0 x 269 x Cos(25) = 5299 J

but for part (b) and (c) i cannot understand what formula to use or how to find an answer for that matter

 

[grzz]

... at a constant speed...

Drawing a FBD and remembering the above quote will lead you to a solution.