# Forces on a door

1. May 13, 2014

### Daltohn

1. The problem statement, all variables and given/known data

A door of uniform thickness is made out of homogenous material. The door's mass is 40 kg, height 2 m, and width 0.8 m. It is hung on two vertical hinges. The hinges are on equal distance from the top and bottom of the door, and the distance between them is 1.50 m. The door puts equal burden on both hinges. Calculate the magnitude of the supporting forces that act on the hinges.

2. Relevant equations
M=Fr, G=mg

3. The attempt at a solution
I put one of the hinges as a point of rotation, r=0.85 and then I calculate the component of G orthogonal to that, G*cos(61.97...). I guess I'm not sure what force I'm supposed to calculate. And how are you supposed to draw the supporting forces? Because if they act on the point of rotation the system would still rotate?

Last edited: May 13, 2014
2. May 13, 2014

### Daltohn

Nvm, got it now.

3. May 13, 2014

### Simon Bridge

Well done - a bit frustrating for people who google to your post looking for an answer though.
Perhaps you can give those folk a model answer to your problem as you see it?