Difference between mechanical rotational reference and rotational free end

Could someone tell me the difference between a mechanical rotational reference and a rotational free end?

I don't understand clearly when I have to use one or the other.

Answer 1

[Isaac]

A Mechanical Rotational Reference block sets the rotational speed to 0 at the port.

A Rotational Free End block allows the rotational speed vary freely without torque.

You can find more information in the documentation too:

• https://www.mathworks.com/help/simscape/ref/mechanicalrotationalreference.html
• https://www.mathworks.com/help/simscape/ref/rotationalfreeend.html