# Moment calculation [closed]

Consider image below. The weight of the fire-fighter is 840 N. What is the torque of the fire-fighter's weight about P and what is the value of the force C which cancels out the torque? • Please check out the FAQ, specifically, "However, we do not allow certain kinds of questions: "Do my homework"-type physics questions "A 4kg ball is traveling at 8m/s in the x direction, how do I find..."" – Mark Eichenlaub May 24 '11 at 13:44
• physics.stackexchange.com/faq – Mark Eichenlaub May 24 '11 at 13:44
• all we will (possibly) give to you are hints, but first you have to provide some details what you have tried so far. In case you don't have a clue where to start, look at wikipedia's entry on torque, and don't forget to use good ol' pythagoras – Tobias Kienzler May 24 '11 at 15:01
• to add to what Tobias said, you should look at some standard resources first. Don't ask us to do your problem for you, but ask about the specific concept that confuses you. – David Z May 24 '11 at 20:15

## 1 Answer

The answer to both your questions are hinted at or can be worked out from the equation: (Horizontal_Force_C) x 12m = (FF_weight) x 5m. You get this equation by summing up the moments around P and setting that sum = 0. You could pick any number of points about which to sum these moments, but point 'P' is the obvious choice for ease of setting up the problem and performing calculations.