I don’t understand how does a rigidbody function works in unity 3d please help me out.
Rigidbodies in Unity defines that the object will interact with the physics like gravity and all. Rigidbody allows you to add mass to a body just like a normal body in the real world which will have mass, weight, will behave differently on different kind of forces and gravity. Similarly Rigidbody in Unity makes you do all these things inside the game. You can add forces, detect collisions, Make the mass of the body according to your need and do a lot of ohysical stuff too. Here is the documentation and some video link for more understanding
http://docs.unity3d.com/Manual/RigidbodiesOverview.html
https://unity3d.com/learn/tutorials/modules/beginner/physics/rigidbody
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