Class method and constructor confusion in java

I have a class that has the duty of creating a simple method with two input parameters. The method needs to be used in the creation of other methods in other classes. My question is, does the way I wrote it seem correct? and when calling this method in another class, what would it look like?

public class IntlDensity {

    static double p = PhysicalConst.pi; 

    public IntlDensity(double m, double r) {
    }

    public double irho (double mass, double rad) {
       return(mass/(((4.0/3)*p*Math.pow(rad, 3))));
    }
}