#ifndef RELATIVISTIC_ROCKET_H
#define RELATIVISTIC_ROCKET_H
#include <cmath>       //for sqrt
#include "rocket.h"
using namespace std;

class relativistic_rocket: public rocket {
public:
	relativistic_rocket(double init_length, double init_v);

	//speed of light in vacuum (meters per second)
	static const double c;

	double length() const override {
		const double fraction {v() / c};
		return rocket::length() * sqrt(1 - fraction * fraction);
	}
};
#endif