Parts of a wave T Wave Height ☺

Which of the unifying themes do you consider the most important of all? why did you say so?

Two paramedics, marlon and brando carry 75-kg man from the scene of an accident to an ambulance using a uniform 5-kg stretcher held by the ends. the stretcher is 7.5m long and the man's center of mass is 1m from brando. how much force must marlon exert to keep the man on the stretcher horizontal? ​

In science who discovered the nucleus and dark stain ​