There was a problem with v1, so I am uploading v2. Please use this one

This was introduced at the "Science Fun Plaza" during the Science and Technology Education 2026 National Conference

It seems that a few high school students can lift 45 degrees

30 degrees is quite difficult, but there are several ways to retrieve them, so please try them

The result will be the same as the problem of whether an object placed on an inclined plane will slide (angle of friction)