# An object with a mass of #12 kg# is on a plane with an incline of # - pi/6 #. If it takes #6 N# to start pushing the object down the plane and #4 N# to keep pushing it, what are the coefficients of static and kinetic friction?

##### 1 Answer

#### Answer:

coefficient of static friction

coefficient of kinetic friction

#### Explanation:

the incline is making an angle of

the forces operating on the body is the weight **m.g** vertically

down = **N**

the normal reaction of the plane acting perpendicular to the plane. say **R**

breaking the weight in components along the plane and

perpendicular to the plane inclined at 30 degree to horizontal

**R** and

**mg. sin30** will act along the plane .

as a force of **6 N** is needed to start the motion

so frictional force **f s = 6 N + mg sin 30 = 6 N + 120/2 = 66 N**

however ,when the body starts moving a force of 4 N is sufficient to maintain the motion , therefore