posted by ivory .
if a 200-g mass is placed at the 20-cm mark (30 cm from the fulcrum), at what mark should a 500-g mass be placed so that the system balances?
The fulcurm is at 50cm, as I understand.
Summing moments about the 50 cm mark. Clockwise moments are positive.
L= 2/5 * 30
so the mark will be 50cm+ L or at the 62cm mark.