What is equivalent to Transform.up when moving and rotating the RigidBody2D component instead?

I am developing a 2D game.

I used to move and rotate my GameObject along a Bezier curve by altering transform properties until I did a little research and found out that using RigidBody2D methods is a lot better way to go with and offers more performance.

However, now I have a problem. I used to set transform.up to the first derivative of Bezier to rotate the object so that it always follows the curve by the right angle.

I can’t find a way to properly rotate my GameObject. How can I achieve the same effect without modifying transform.up? What is equivalent to transform.up when using RigidBody2D?

Thank you!

If anyone ever visits this question and has the same problem, this is the code to do it:

// Move the character
// transform.position = bezier;
rigidBody.MovePosition(bezier);

// Rotate the character so that the top of the sprite always lies on the curve
// transform.up = firstDerivativeBezier;
float anglesToRotate = Mathf.Atan2(firstDerivativeBezier.y, firstDerivativeBezier.x) * Mathf.Rad2Deg - 90f;
rigidBody.MoveRotation(anglesToRotate);

And the answer lies here:

https://math.stackexchange.com/questions/477165/find-angle-at-point-on-bezier-curve