You decided to use a loader and $15-$cubic$-$yard dump trucks $($manufacturer$\text{'}$s performance

data is shown in the Table $1)$ to haul the material from the borrow to the construction sites.

The trucks are powered with $185-$horsepower, four cycle naturally respirated engines, and

the gear train efficiency is estimated to be $0\mathrm{.}8.$ The road has an average uphill grade of

$2\mathrm{.}5\%$ when travelling from the borrow site to the construction site. The project site is at the

elevation of $2,000$ feet. The gross weight of the fully loaded truck is $35$ tons and $60\%$ of

the loaded weight is carried by the rear driving wheels. Tire penetration is estimated to be

$1\mathrm{.}5$ inches and the coefficient of traction is estimated to be $0\mathrm{.}6.$ The trucks are not equipped

with radial tires.

a$.$ What is the maximum speed of a fully loaded truck traveling from the borrow site to

the construction site?

b$.$ What would be the answer for part a$,$ if you use the trucks with turbocharged diesel

engines?

Table $1.$ Manufacturer's performance data