Chapter 1.7, Problem 27P

A)

Interpretation Introduction

Interpretation:

The power required to $\left(\dot{W}\right)$ driving the wagons has to be determined.

Concept introduction:

The power driving the wagons is equal to the power produced by the 20 mule team

1 hp = 1 mule power.

The required power $\left(\dot{W}\right)$ to drive the wagons is,

$\dot{W}={\text{hp}}_{\text{provided}\text{by}\text{20-mule}\text{teams}}$

Here, horsepower provided by 20-mule teams is ${\text{hp}}_{\text{provided}\text{by}\text{20-mule}\text{teams}}$.

B)

Interpretation Introduction

Interpretation:

Conversion of the value of $\text{10,000}\text{calories}$ of  heat into BTU.

Concept introduction:

1 calorie is equal to 4.184 joules.

1 calorie is equal to $39.66\times {\text{10}}^{-4}\text{BTU}$.

C)

Interpretation Introduction

Interpretation:

Conversion of the value of $\text{100,000}\text{calories}$ work in $\text{1}\text{minute}$ into horsepower

Concept introduction:

1 min= 60 s

1 W =1 J/s

1 hp =746 W