Introduction to Parameters and Objects - Building Java Programs: A Back to Basics Approach - page 175

6 // constant for Earth acceleration in meters/second^2
7 public static final double ACCELERATION = 9.81;
8
9 public static void main(String[] args) {
10 Scanner console = new Scanner(System.in);
11 giveIntro();
12
13 System.out.print("velocity (meters/second)? ");
14 double velocity = console.nextDouble();
15 System.out.print("angle (degrees)? ");
16 double angle = Math.toRadians(console.nextDouble());
17 System.out.print("number of steps to display? ");
18 int steps = console.nextInt();
19 System.out.println();
20
21 printTable(velocity, angle, steps);
22 }
23
24 // prints a table showing the trajectory of an object given
25 // its initial velocity and angle and including the given
26 // number of steps in the table
27 public static void printTable( double velocity,
28 double angle, int steps) {
29 double xVelocity = velocity * Math.cos(angle);
30 double yVelocity = velocity * Math.sin(angle);
31 double totalTime = 2.0 * yVelocity / ACCELERATION;
32 double timeIncrement = totalTime / steps;
33 double xIncrement = xVelocity * timeIncrement;
34
35 double x = 0.0;
36 double y = 0.0;
37 double t = 0.0;
38 System.out.println("step\tx\ty\ttime");
39 System.out.println("0\t0.0\t0.0\t0.0");
40 for ( int i = 1; i <= steps; i++) {
41 t += timeIncrement;
42 x += xIncrement;
43 y = displacement(yVelocity, t, ACCELERATION);
44 System.out.println(i + "\t" + round2(x) + "\t" +
45 round2(y) + "\t" + round2(t));

46 }
47 }
48
49 // gives a brief introduction to the user