$(10$ points maximum value$).$ Mobile equipment power requirements$-$ Rimpull and coefficient of traction. See equations, p$.10$ and Table $6\mathrm{.}4,$ p$.10.$

a$.$ Calculate the Rimpull capacity for a $220HP$ truck operated at $8\mathrm{.}0MPH$ in second gear, assuming $85\%$ efficiency.

b$.$ Calculate the minimum required Coefficient of Traction for a wheeled scraper. Assume the scraper weighs $72,000lb$ empty with fuel and oil. Assume its capacity is $32cy$ heaped. The scraper is moving loose dry sand with a bulk unit weight of $105$ pcf$.54\%$ of the total vehicle weight and soil load is on the drive wheels. Assume Rimpull capacity of the scraper is $40,000lb$ for the job conditions.

c$.$ Is the calculated coefficient of traction sufficient for the loose dry sand? Use attached Table $6\mathrm{.}4$ to look up available c$$efficient of traction for various soil conditions.