# Finding the contact force in a mechanical problem [closed]

what is the proper FBD for this system. I cant decide since the weight is given, but there is tension and contact forces. Things get mixed up.

Determine the contact force between the smooth 200-lb ball B and the horizontal bar, and the magnitude of the pin reaction at A. Neglect the weights of the bar and the pulley.

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## closed as too localized by Qmechanic♦, dmckee♦Feb 13 '12 at 17:49

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Welcome to Physics.SE! I'm afraid that the FAQ is very clear that these kinds of "Here is a basic problem, please show me the solution" questions are off topic. If you can re-formulate this question in terms of the principles at work you could get it re-opened. Of course, if you expressed it in terms of the basic principle you'd probably see the answer right away. Hint: are the masses, $B$ and $C$, under acceleration? What does that say about the sum of the forces acting on them? – dmckee Feb 13 '12 at 17:49

## 1 Answer

Use two conditions: 1. The sum of forces acting on B (T,N,mg) is zero; 2. The sum of moments of forces (T at C, N at B) applied to the pin with respect to point A is zero. Choose the signs carefully.

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