The only way to move the centre of gravity below the rope is to have a mass larger than the person, suspended from the person, with the larger mass below the rope level. Person who told you to change 'over' to under needs to urgently review his/her Physics knowledge...
I tutor Chemistry, Physics and Biology, as well as A/Emath on the sidelines. Will attend to questions on these subjects, time permitting. Little or no time during the exam period, as I will be busy working to prepare my students to score well.

Get expert help for Emath, Amath, Physics and Chemistry at Eton Tuition Centre (next to Hougang Mall). Tel: 63853133 A friends Centre, where I tutor O-level Chemistry.