The program should be in java. The average person can jump off the ground with a

Question

The program should be in java. The average person can jump off the ground with a velocity of 7 mph without fear of leaving the planet. However, if an astronaut jumps with this velocity while standing on Halley’s Comet, will the astronaut ever come back down? Create a program that allows the user to input a launch velocity (in mph) from the surface of Halley’s Comet and determine whether a jumper will return to the surface. If not, the program should calculate how much more massive the comet must be in order to return the jumper to the surface.

Explanation / Answer

/** * EscapeVelocity.java - * Calculates if your jump causes you to leave planetary gravity. * * @author ethan.lee * */ import java.util.Scanner; public class EscapeVelocity { /** Scanner to read all user inputs **/ private static Scanner prompt; /** Gravitational constant (go physics!) **/ static final double GRAVITATIONAL_CONSTANT = 6.67E-11; /** Mass of Halley's comet. **/ static final double HALLEYS_COMET_MASS = 1.3E+22; /** Radius of Halley's comet. **/ static final double HALLEYS_COMET_RAD = 1.153E+6; /** Conversion constant from m/s to mph **/ static final double METERS_SECONDS_TO_MILES_HOURS = 2.23694; /** * Runs the program, takes input, processes. * @param args Array of runtime arguments **/ public static void main(String[] args) { System.out.println("Enter the velocity (in mph) " + "of your jump from Halley's Comet."); prompt = new Scanner(System.in); double velocity; while(!prompt.hasNextDouble()) { System.out.println("Invalid input. " + "Requires floating point number. Try again."); prompt.next(); } velocity = prompt.nextDouble(); double escVelocity = Math.sqrt((2 * GRAVITATIONAL_CONSTANT * HALLEYS_COMET_MASS) / HALLEYS_COMET_RAD); if(velocity > escVelocity * METERS_SECONDS_TO_MILES_HOURS) { System.out.println("Zounds! You've jumped straight " + "off of Halley's comet!"); } else { System.out.println("Phew, you're still on the comet. " + "Hang on!"); } } }

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