What is a Rigidbody?

Learn the role of the Rigidbody component in physics simulation.

What is a Rigidbody?

The Rigidbody component enables a GameObject to be governed by Unity's physics engine (Nvidia PhysX). Adding this component allows the object to move realistically according to gravity, friction, and acceleration.

// Accessing Rigidbody and enabling gravity
Rigidbody rb = GetComponent<Rigidbody>();
rb.useGravity = true;

Objects lacking a Rigidbody are treated as static and cannot be pushed or dropped by physics forces.

Mass and Kinematic settings

The mass property on a Rigidbody defines its weight in kilograms. When isKinematic is set to true, the object ignores physics forces and only moves via script or animation.

rb.mass = 2.5f;
rb.isKinematic = false;

For example, a moving elevator platform typically uses isKinematic = true so it does not wobble from physical impacts.

Exercise Print Rigidbody state

Assign 3 to mass and "Enabled" to gravity. Print Rigidbody Mass: 3 | Gravity: Enabled to the console.

Show example solution

using System;

class Program
{
    static void Main()
    {
        int mass = 3;
        string gravity = "Enabled";
        Console.WriteLine("Rigidbody Mass: " + mass + " | Gravity: " + gravity);
    }
}

Test yourself

What is the primary role of the Rigidbody component in Unity?
- Granting gravity, mass, and physics simulation capabilities to an object
- Playing background audio files in an infinite loop
- Calculating the brightness angle of scene light sources
- Only changing the 2D UI pixel resolution of an object
Show answer

Granting gravity, mass, and physics simulation capabilities to an object — Rigidbody brings the object into the physics calculation cycle, providing mass and gravity.
Enable gravity
```
rb.____ = true;
```
Show answer
```
rb.useGravity = true;
```
Rigidbody properties

Rigidbody

Manages physics simulation — component
mass

Object mass in kilograms
useGravity

Toggles gravity effect — property
isKinematic

Exempts object from physics forces

Next lesson: What is a Collider?

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