A particle of mass m, moves along the uniformly rough track PQR as shown in the figure. The coefficient of friction (μs=μk=μ), between the particle and the rough track is equal throughout the track. The particle is released from rest, from the point P and it comes to rest again at point R. The energy lost by the particle, over the parts PQ and QR of the track are equal and no energy is lost when the particle changes direction from PQ to QR. Then, values of the distance x=QR and coefficient of friction μ are respectively close to: