The hinge permits one degree of freedom between two objects.
Physics of a door hinge.
Ignoring dampening mechanisms of door closer i have no idea how they work.
And it is generally held to the door and door jamb via screws although nails can also be used.
And the additional stress this puts on the hinges is what causes the dragging problem when i look closely at the gate the top hinge is clearly stretched somewhat to the right and the bottom.
Ignoring friction air resistance gravity entirely.
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Because gravity works on a door in this way hinges are placed on the high side with the bottom hinge 10 inches from the bottom of the door and the top one 5 inches from the top of the door.
A door hinge combines 2 simple machines the wheel and the axle.
The doors have two sets of hinges equidistant from the center of the door again for simplicity the doors are fully open when they reach an angle theta open frac pi 2 from the frame.
Translation is completely constrained.
2 of course physics isn t the only reason to put the knob at the edge of the door it also allows you to easily integrate the latching mechanism to hold the door closed with the knob.
You could have a door without hinges.
It has elements of the lever as well.