This is the boss. No calculator: today $g = 10\ \mathrm{m/s^2}$, the round number every physicist keeps for mental work, and the ramp is pinned at $37^\circ$ so that $\sin 37^\circ = 0.6$ and $\cos 37^\circ = 0.8$ — the 3-4-5 triangle, doing what it has done since Grade 9. Every value is chosen to fit in your head.

One crate, one long problem, and every answer feeds the next: the weight, then the press into the ramp, then the pull down it, then friction's cut of the press, then Newton on what survives, then the speed it all buys. Write each line down as you go — one early slip rolls the whole way to the bottom, and the finish screen will show you exactly where it started.

Then one bonus mark that uses no numbers at all, only the comparison this chapter has been building toward. 5★ under par here is the chapter crown. Clock in.