posted by can't understand the question...help!!! .
A door, essentially a uniform rectangle of height 2.00 m, width 0.78 m, and weight 136.0 N, is supported at one edge by two hinges, one 18.1 cm above the bottom of the door and one 181.9 cm above the bottom of the door. Calculate the horizontal components of the forces on the two hinges.
lower hinge magnitude
upper hinge magnitude
I wish I understand what you think you don't know.
the door has a center of gravity.
You can label each hing with a horizontal force, and a vertical force.
Then, write three equations
Sum of horizontal forces=0
sum of vertical forces=0
sum of moments about any point is zero
so with those equations, you get the forces on each hings. All it is looking for is horizontal force (note: the two hinges will be equal and opposite horizontal forces.