Abstraction in java

abstract class Vehicle{
    abstract void start();
}
class car extends Vehicle{
    void start(){
        System.out.println("car start with key");
    }
}
class Scooter extends Vehicle{
    void start(){
        System.out.println("scooter start with kick");
    }
    public static void main(String args[]){
        car c=new car();
        c.start();
        Scooter s=new Scooter();
        s.start();

    }
}