Question

How cold is it outside? The temperature alone is not enough to provide the answer. Other factors including wind speed, relative humidity, and sunshine play important roles in determining coldness outside. In 2001, the National Weather Service (NWS) implemented the new wind-chill temperature to measure the coldness using temperature and wind speed. The formula is:

t_wc = 35.74 + 0.6215t_a - 35.75v^0.16 + 0.4275t_av^0.16

t w c = 3.74 + 0.6215 t a − 35.75 v 0.16 + 0.4275 t a v 0.16

where t_a is the outside temperature measured in degrees Fahrenheit, v is the speed measured in miles per hour, and t_wc is the wind-chill temperature. The formula cannot be used for wind speeds below 2mph or temperatures below -58°F or above 41°F.

Write a program that prompts the user to enter a temperature between -58°F and 41°F and a wind speed greater than or equal to 2 then displays the wind-chill temperature. Use Math.pow(a, b) to compute v^0.16. Your class must be named Windchill. Here is a sample run:

Enter a temperature between -58°F and 41°F: 5.3
Enter the wind speed (>= 2) in miles per hour: 6
The wind chill index is -5.567068455881625

This is what I made:

import java.util.Scanner;
public class Windchill
{
public static void main(String[]args)
{
//create Scanner
Scanner s=new Scanner(System.in);
double ta= 5.3;
int v= 6;
double v2= Math.pow(v,.16);
double Windchill= 35.74 + 0.6215 * ta-35.75 * v2+0.4275 * ta * v2;
//get temperature in Fahrenheit
System.out.println("Enter a temperature between -58°F and 41°F:" +" "+ ta);
//get wind speed
System.out.println("Enter the wind speed (>= 2) in miles per hour"+" "+ v);
//get windchill index
System.out.println("The windchill index is"+" "+ Windchill);
}
}

My teacher told me: "your program needs to let the user enter the temperature and wind speed at the keyboard."

How do I fix this? please help.

Answer 1

Please find the updated java program below:

////////////////////Windchill.java////////////////////

import java.util.Scanner;
/**
* Class: Windchill
*   1.    Instead of taking direct values for variables ta and v,
*   scanner instance(s) is used to read double and int value from user console.
*   2. An if condition is introduced to check if the formula can be used or not i.e to print a message
*   if value of v is less than 2 or ta is less than -58 or greater than 41
*/
public class Windchill
{
   public static void main(String[]args)
   {
       //create Scanner
       Scanner s=new Scanner(System.in);
      
       //get temperature in Fahrenheit
       System.out.println("Enter a temperature between -58°F and 41°F:");
       double ta = s.nextDouble();//read the double value from console
      
       //get wind speed
       System.out.println("Enter the wind speed (>= 2) in miles per hour:");
       int v = s.nextInt(); //read the integer value from console
      
       s.close(); //close the scanner as all user inputs are taken
      
       if(v < 2 || ta < -58 || ta > 41){//check if the formula can be used
           System.out.println("The windchill index cannot be measured for wind speeds "
                   + "below 2mph or temperatures below -58°F or above 41°F.");
       }else{
           double v2= Math.pow(v,0.16);//get v0.16  
           //using the formula
           double windchill= 35.74 + 0.6215 * ta -35.75 * v2 + 0.4275 * ta * v2;      
           //print windchill index
           System.out.println("The windchill index is"+" "+ windchill);
       }
   }
}

============================================

OUTPUT

===========================================

RUN1

Enter a temperature between -58°F and 41°F:
5.3
Enter the wind speed (>= 2) in miles per hour:
6
The windchill index is -5.567068455881625

RUN2

Enter a temperature between -58°F and 41°F:
-60
Enter the wind speed (>= 2) in miles per hour:
5
The windchill index cannot be measured for wind speeds below 2mph or temperatures below -58°F or above 41°F.