This is the boss. No calculator — today $g = 10\ \mathrm{m/s^2}$, the round number every engineer keeps for mental work, and the draws are chosen to fit in your head. One lift, one ramp, and every answer feeds the next: weight, then the rope's win over it, then Newton, then the speed that acceleration buys, then the climb, then the verdict the commissioning sheet actually wants.

Write each line down. A cascade is honest but unforgiving — one slip in line two propagates all the way to the sign-off, and the finish will show you exactly where it started. The last stage is a judgement, not a number: pass or fail against the sheet. That is what the whole chain was for.

Everything from the chapter rides in it. 5★ under par here is the chapter crown. Clock in.