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I know that there is kinetic friction, experienced by an object in motion, and static friction, experienced by a stationary object put into motion.
Take an object that is pushed, this push makes the object go partway up a hill, before it starts falling back down the hill. When the object comes to the peak of it's movement up the hill does it experience static friction?
This will help :
You are asking about a threshold of motion, stopped before it falls back, so there will be the static friction equal to the one in the threshold of motion.
The difference between static and kinetic coefficients obtained in simple experiments like wooden blocks sliding on wooden inclines roughly follows the model depicted in the friction plot from which the illustration above is taken. This difference may arise from irregularities, surface contaminants, etc. which defy precise description. When such experiments are carried out with smooth metal blocks which are carefully cleaned, the difference between static and kinetic coefficients tends to disappear. When coefficients of friction are quoted for specific surface combinations are quoted, it is the kinetic coefficient which is generally quoted since it is the more reliable number.
