5 A particle \(P\) of mass 0.4 kg is released from rest at the top of a smooth plane inclined at \(30 ^ { \circ }\) to the horizontal. The motion of \(P\) down the slope is opposed by a force of magnitude \(0.6 x \mathrm {~N}\), where \(x \mathrm {~m}\) is the distance \(P\) has travelled down the slope. \(P\) comes to rest before reaching the foot of the slope. Calculate

1. the greatest speed of \(P\) during its motion,
2. the distance travelled by \(P\) during its motion.