I've decided to do some mythbusting.
This frame is often used as an important example of Ranma's lifting weight limit.
...But, as the image says, all the numberы are meaningless. Resistance is futile.
We are never shown her lifting it, only pushing it sideways. Considering she was approaching Orochi from above when she saw him about to chew Akane's skull open... She could have plucked the rock from one of the nearby cave walls, then directed it. She could have *rolled* it across the cave floor: it's round. In short, this particular example says us nothing. There are *no* frames showing the rock before this one, no way to know where it came from.
Myth busted. No 30-ton lifting limit for you, Ranma.