# Calculating reaction forces on 3d object

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1. Oct 25, 2015

### iqjump123

Hello all,

I am in the process of calculating reaction forces on an object, and need some help.

Attached is a free body diagram of an object in two different views- one looking from the sides (z-x plane) and one looking it in birds eye view. (xy plane)

7 variables I am looking to solve are:
horizontal and vertical force components of two parts, and force component of rear part. (r1,v1, r2, v2, f1, f2, f) The first two parts can react only in two directions, and the last two parts can only react in one diagonal direction (45 deg), totalling to 4 parts that I need reactions for.

given are all of the dimensions and F_cg, a gravity force acting on the object in the x direction.

I have listed out what I think are the equations needed in the picture.
I am not getting a viable solution though.

Feel free to let me know the issues with my approach.

#### Attached Files:

• ###### passembly.png
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28 KB
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108
2. Oct 26, 2015

### Simon Bridge

When dealing with 3D objects, you want to represent applied forces in terms of radial and tangential components wrt the center of mass of the object.
To get reaction forces, in context, you need to see the rest of the situation ... i.e. the other bodies involved.