# A beam question

1. Jun 7, 2005

### afromanam

ok, i don't know how to start this problem

the beam in the drawing weighs 3000 kg. It is attached to the wall by means of a simple union and without friction in point A. It is attached to the wall by means of a cable CD. The moment applied in point B is 6000 kg*m. Calculate graphically the force in point A and tension in cable CD:

lots of questions here:

0) when they say graphically... what exactly do the mean? you know, that you have to draw the lines with their exact length and their angle and with a ruler measure the resultant force...

1) UNITS: the kilograms here are kilograms force?, or should i convert them to newtons?

2) REACTION IN POINT A: I assume there will be a reaction in the X and Y axis.

3) the main question here is: the momentum applied, how should i consider it when balancing the forces, does this thing have to do with flexural moments and that stuff? or i just translate the momentum applied to F*d?

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2. Jun 7, 2005

### Pyrrhus

Remember that unlike the force, that can only move along its line of action without doing a force-couple (force momentum) system, the momentum is a free vector and you can put it anywhere.

The momentum will only affect the sum of moments equation.

$$\sum \tau$$ also represented as $$\sum M$$

Notice calculating sum of momentum on point B, won't make it 0 (It's a Free Vector).

3. Jun 7, 2005

### afromanam

thanks a lot, i really appreciate it

and i really hope you're Somewhere in the Sunny Caribbean