4 A particle moves up a line of greatest slope of a rough plane inclined at an angle \(\alpha\) to the horizontal, where \(\cos \alpha = 0.96\) and \(\sin \alpha = 0.28\).
- Given that the normal component of the contact force acting on the particle has magnitude 1.2 N , find the mass of the particle.
- Given also that the frictional component of the contact force acting on the particle has magnitude 0.4 N , find the deceleration of the particle.
The particle comes to rest on reaching the point \(X\).
- Determine whether the particle remains at \(X\) or whether it starts to move down the plane.