How can i make game object to orbit another (using rigidbody2d)

Questions & Answers
1

how can i make game object to orbit another (using rigidbody2d)
i would like gameobject with rigidbody2d to orbit around the target point. i want to use physics with my gameobject to attain this functionality. Please help me with this Thank you Amir Yatoo

2

You can simply simulate gravity. The equation to get the force exacted by gravity on an object given the mass of the attracter, distance to attracter, and gravitational constant is

g = GM/r^2

where G is the gravitational constant (strength of gravity per unit of mass), M is the mass of the attracting object, and r is the distance between the center of the attracting object and the object being attracted.

Here’s a quick script I wrote.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class OrbiterScript : MonoBehaviour {

    public GameObject attracter; // Set this to the gameobject that this gameobject will be attracted to 

    public float gravityConstant; // Affects strength of gravity

    public Vector2 startVelocity; // This will be the starting velocity of our second object (it needs to have velocity in order to orbit)

    private Rigidbody2D rb;

    private float attracterMass;

	// Use this for initialization
	void Start () {
        rb = this.GetComponent<Rigidbody2D>();
        attracterMass = attracter.GetComponent<Rigidbody2D>().mass;

        rb.velocity = startVelocity;
	}
	
	// FixedUpdate is called once per physics update
	void FixedUpdate () {
        float distance = Vector2.Distance(this.transform.position, attracter.transform.position); // Distance between us and attracter
        Vector2 unrotatedForce = (Vector2.right * gravityConstant * attracterMass) / Mathf.Pow(distance, 2); // Magnitude of force due to gravity

        // Now we have to rotate that force so it's pointing towards the attracter
        Vector2 posDifference = attracter.transform.position - this.transform.position; // Difference in position
        float angleDifference = Mathf.Atan2(posDifference.y, posDifference.x); // Now, difference in angle

        // Now we use some trig to rotate the force vector from pointing right to pointing at the attracting object
        Vector2 rotatedForce = new Vector2(unrotatedForce.x * Mathf.Cos(angleDifference) - unrotatedForce.y * Mathf.Sin(angleDifference),
                unrotatedForce.x * Mathf.Sin(angleDifference) + unrotatedForce.y * Mathf.Cos(angleDifference));

        // And now we simply add the force to our rigidbody
        rb.AddForce(rotatedForce);
	}
}

Simply attach this script to a Sprite or some other 2D object with an associated Rigidbody2D, set the “Attracter” field to a reference of the object that this object is rotating around, then set the gravity constant (force of gravity multiplier) and starting velocity, and you’re good to go.