5 A puck, of mass 0.2 kg , is placed on a slope inclined at \(20 ^ { \circ }\) above the horizontal, as shown in the diagram.
\includegraphics[max width=\textwidth, alt={}, center]{217f0e3e-9d1b-41f1-8299-f56d073fbbeb-3_280_773_1249_623} The puck is hit so that initially it moves with a velocity of \(4 \mathrm {~ms} ^ { - 1 }\) directly up the slope.

1. A simple model assumes that the surface of the slope is smooth.
   1. Show that the acceleration of the puck up the slope is \(- 3.35 \mathrm {~m} \mathrm {~s} ^ { - 2 }\), correct to three significant figures.
   2. Find the distance that the puck will travel before it comes to rest.
   3. What will happen to the puck after it comes to rest? Explain why.
2. A revised model assumes that the surface is rough and that the coefficient of friction between the puck and the surface is 0.5 .
   1. Show that the magnitude of the friction force acting on the puck during this motion is 0.921 N , correct to three significant figures.
   2. Find the acceleration of the puck up the slope.
   3. What will happen to the puck after it comes to rest in this case? Explain why.