Java Newton's Method HELP PLEASE

Hey I'm pretty new to java and I was just wondering if there was a way that I can reduce the amount of iterations performed? I'm getting about 237 right now, and I'd like to know how to get less.

Thanks so much here's my code:

Code :

import java.io.*;
 
public class Assignment1try2
 
{
 
    public static void main(String[] args)
 
    {
        //Exports the data to an excel file
 
     PrintWriter outputFile = null;
       try
         {
           outputFile = new PrintWriter(new FileOutputStream("outputVelomobile.xls",false));
          }
            catch(FileNotFoundException e)
         {
           System.out.println("File error.  Program aborted.");
           System.exit(0);
          }
 
 
        //Variable declarations for the Quest Velomobile
 
    double n = 0.92;
    double rho = 1.20;
    double cR = 0.004;
    double m = 32+80;
    double g = 9.81;
    double cD = 0.24;
    double area = 0.46;
    double valueOne = rho*cD*area;
    double valueTwo = cR*m*g;
    double initialRootEstimate = 1;
    double function, absDifference;
    double[] rootEstimate = new double[8];
    int numLoops = 0;
    int[] powerRider = {25,50,75,100,150,200,300,400};
 
 
        //Start loop
    for (int index=0;index<powerRider.length;index++)
 
    {
 
         numLoops = 0;
 
        do
        {
 
        function = -n*powerRider[index] + 0.5*(valueOne*(Math.pow(initialRootEstimate,3))) + (valueTwo*initialRootEstimate);
 
        rootEstimate[index] = initialRootEstimate - (function/((3/2)*(valueOne*(Math.pow(initialRootEstimate,2))) + (valueTwo)));
 
        absDifference = Math.abs(rootEstimate[index] - initialRootEstimate);
 
        initialRootEstimate = rootEstimate[index];
        numLoops++;
 
         }
 
           while (absDifference >=1.0E-12);
 
            //Displays data on screen
            System.out.println();
            System.out.println("The Power is:"    +   powerRider[index]);
            System.out.println("The Root Estimate is:"    +   initialRootEstimate);
            System.out.println("The number of cycles is:"    +   numLoops);
            System.out.println();
 
            //Outputs results on screen
 
            outputFile.println();
            outputFile.println("The Power is:"    +   powerRider[index]);
            outputFile.println("The Root Estimate is:"    +   initialRootEstimate);
            outputFile.println("The number of cycles is:"    +   numLoops);
            outputFile.println();
 
 
        }
            outputFile.close();
    }
 
}