A door has a height of 2.1 m along a y axis that extends vertically upward and a width of 0.830 m along an x axis that extends outward from the hinged edge of the door. A hinge 0.41 m from the top and a hinge 0.41 m from the bottom each support half the door's mass, which is 20 kg. In unit-vector notation, what are the forces on the door at (a) the top hinge and (b) the bottom hinge

Will you chech and finish these for me, because i am stumped with them.

Why does the equilibrium position of the spring change when a mass is added to the spring? will the mass oscillate around the new equilibrium position of the spring or the previous position without a mass attached to the spring? if the equilibrium position of the spring changes by 20 cm (assuming no initial mass) when a mass is added to the spring with constant 4.9 kg/s^2, what is the mass of the object attached to the spring?

What happens when the vapor pressure of a liquid is equal to the external pressure?