A particle is projected from a point P with initial speed u m s^-1 up a line of greatest slope PQR of a rough inclined plane. The distances PQ and QR are both equal to 0.8 m. The particle takes 0.6 s to travel from P to Q and 1 s to travel from Q to R.

1. Show that the deceleration of the particle is \(\frac{2}{3}\) m s^-2 and hence find u, giving your answer as an exact fraction.
2. Given that the plane is inclined at 3° to the horizontal, find the value of the coefficient of friction between the particle and the plane.