Figure 3.1

/* mass2energy.cpp computes energy from a given mass using
* Einstein’s mass-to-energy conversion equation.
*
* Input: The mass (in kilograms) being converted to energy
* Precondition: mass >= 0
* Output: The amount of energy (in kilojoules) corresponding
* to mass
*******************************************************************/
#include <iostream> // cin, cout, <<, >>
#include <cassert> // assert()
#include <cmath> // pow()
using namespace std;
int main()
{
	const double SPEED_OF_LIGHT = 2.997925e8; 	// meters/sec
	cout << "To find the amount of energy obtained from a given mass,\n"
	     << "enter a mass (in kilograms): ";
	double mass;
	cin >> mass; 					// get mass
	assert(mass >= 0); 				// make sure it's nonnegative
		// compute energy
	double energy = mass * pow(SPEED_OF_LIGHT, 2);
		// display energy
	cout << mass << " kilograms of matter will release "
	     << energy << " kilojoules of energy.\n";
}

Sample Runs for Figure 3.1

To find the amount of energy obtained from a given mass,
enter a mass (in kilograms): 1

1 kilograms of matter will release 8.98755e+16 kilojoules of energy.

To find the amount of energy obtained from a given mass,
enter a mass (in kilograms): 2

2 kilograms of matter will release 1.79751e+17 kilojoules of energy.

To find the amount of energy obtained from a given mass,
enter a mass (in kilograms): 125.5

125.5 kilograms of matter will release 1.12794e+19 kilojoules of energy.

Figure 3.2

/* tripCost.cpp calculates the total cost and miles per gallon
* of a vehicle, based on the miles traveled, fuel consumed,
* cost per gallon of fuel, and operating cost per mile.
*
* Input: The total miles traveled, total fuel consumed,
* unit cost of the fuel, and operating cost per mile.
* Precondition: miles, gallonsOfFuel, unitFuelCost and
* unitOperatingCost are all positive.
* Output: The miles per gallon, total cost of the trip
* and the cost per mile.
***************************************************************/
#include <iostream> 	// cin, cout, <<, >>, fixed, showpoint
#include <iomanip> 	// setw(), setprecision()
#include <cassert>
using namespace std;
int main()
{
	const int WIDTH = 7; // width of output field
	cout << "Enter:\n\ttotal miles traveled,"
		<< "\n\tgallons of fuel used,"
		<< "\n\ttotal cost per gallon of the fuel, and"
		<< "\n\toperating cost per mile."
		<< "\n\t---> ";
	double miles, 			// total miles traveled
		gallonsOfFuel, 		// total gallons used
		unitFuelCost, 		// fuel cost per gallon
		unitOperatingCost; 	// operating cost per mile
	cin >> miles >> gallonsOfFuel
		>> unitFuelCost >> unitOperatingCost;
	assert(miles > 0 && gallonsOfFuel > 0 &&
		unitFuelCost > 0 && unitOperatingCost > 0);
	double milesPerGallon = miles / gallonsOfFuel,
	fuelCost = unitFuelCost * gallonsOfFuel,
	operatingCost = unitOperatingCost * miles,
	totalTripCost = fuelCost + operatingCost,
	costPerMile = totalTripCost / miles;
	cout << showpoint << fixed << setprecision(2)
		<< "\n\tMiles per gallon: " << setw(WIDTH) << milesPerGallon
		<< "\n\tTotal cost: $" << setw(WIDTH) << totalTripCost
		<< "\n\tCost per mile: $" << setw(WIDTH) << costPerMile
		<< endl << endl;
}

Sample Runs for Figure 3.2

Enter:
	total miles traveled,
	gallons of fuel used,
	total cost per gallon of the fuel, and
	operating cost per mile.
	---> 10 1 1.50 3.50

Miles per gallon: 10.00
Total cost: $ 36.50
Cost per mile: $ 3.50

Enter:
	the total miles traveled,
	the gallons of fuel used,
	the total cost per gallon of the fuel, and
	the operating cost per mile.
	---> 100 10 15 10

Miles per gallon: 10.00
Total cost: $1150.00
Cost per mile: $ 11.50