A wheelbarrow is also a second class lever.
Second hinge of the door.
Most of these very early hinges are bronze door hinges.
A door belongs to the second class of levers because its pivot hinge is at the end the load weight of the door is at the center while the effort opening the door is applied at the other end.
Hinges have been found in ancient societies in africa asia europe and elsewhere.
If each hinge supports half the weight of the door find the magnitude and direction of the horizontal components of the forces exerted by the two hinges on the door.
The first is the pivot and the second is the bracket.
The pivot allows the door to be opened at a 90 degree angle.
If your right hand is nearer the doorknob then it is a right handed hinge and door.
However it is seen on interior doors from time to time.
Akkadian and hittite panache was so great the massive palaces sacred structures and protective gates they built had heavy doors that operated with load bearing metal hinges.
Another way to determine the door hinge direction is to open the door and stand with your back against the hinge jamb or area.
If your left hand is nearer the doorknob then it is a left handed hinge and door.
This hinge is installed against the recess in the door where it is impossible to view from the outside.