# Static, Moment

## Homework Statement

The wall crane in Fig. 3 supports a load of 800 N. Determine the horizontal and vertical
components of reaction at the pins A and D. Also, what is the force in the cable at the winch
W?
[URL=http://imageshack.us][PLAIN]http://img182.imageshack.us/img182/992/tutorialse0.jpg[/URL] http://g.imageshack.us/g.php?h=182&i=tutorialse0.jpg [Broken][/PLAIN]

## Homework Equations

Newton's Laws of Motion, Moment, Equilibrium of Forces

## The Attempt at a Solution

First I draw a free body diagram at B. The vertical forces involved are the y component of the tension in rod BD and the y component of the tension of cable WB.

Since the tension of a massless cable is the same throughout the string, the tension of the cable is 400N. Substituting the value of TWB to the above equation, I get TBD=490N.

However, a problem occurs when I attempt to find TBD by taking the moment at A. The solution for TBD turns out to be 2752N.

What cause the difference in the answer?

Last edited by a moderator: