first clear ur concept from book HC Verma or Dc pandey choose any one ....
after solve numericals .... 
						

							
FRICTION:-The force opposed on any body which is in motion to reduce the motion is called friction.
There are three types of friction.they are:-
(1)Static friction(or)limiting friction.(fs) 

(2)kinetic friction(or)dynamic friction.(fk) 

(3)rolling friction.(fr)
fs=Us.N   for further information type the question and mail to the address. 

						

							
ITS SIMPLE
 
 
ALWAYS TAKE FRICTION IN OPPOSITE DIRECTION OF MOTION       ,............ BUT IN CASE OF ROTATIONAL U WILL HV TO ANALYZE THE PROBLEM
EX: CAR MOVING IN +X AXIS DIRECTION FRITCTION FORCE WILL ALSO ACT IN SAME DIRECTION OF MOTION
TO UNDERSTAND THIS
CONSIDER
THE WHEELS OF CAR AND SEE TANGENTIAL VELOCITY ITS TOWARDS  -VE X AXIS
 
 
 
FRICTIONAL FORCE IS GIVEN BY
COEFFICENT OF FRICITON*NORMAL FORCE IN ANY CASE..............
IN CASE OF INCLINATION RESOLVE FORCES IN X AND Y DIRECTIONS
 
U CAN REFER TO HC VERMA SURELY IT WILL MAKE UR BASIC CLEAR