Unit 6 Chapter 4 Moments of forces 2D If forces acting on a body are not concurrent they tend to rotate the body Mathematically model the effect of force FH at point O Method 1 Definition of moment and geometry Method 2 Use components of force Method 3 Use cross product Definition of a moment Moment of a force about a point is a measure of tendency of force to rotate the body about a point Moment is vector has magnitude and direction Magnitude defined as Direction Moment examples L A A A A F F F F Method 1 Calculate Moment of a Force Use definition of moment geometry to determine d and intuition to determine direction of rotation Use method 1 Determine the moment of the force about point A Use method 1 Determine the moment of F 200 N about point A Method 2 Use components of force Principle of Moments The moment of a force of the resultant of a system of forces with respect to a point the sum of the moments of the individual forces about the same point Method 2 Use Fx Fy components to get moment of F about a point F A Direction of Moments using Right Hand Rule Determine the direction of the moment of 275 lb force about point A Use Method 2 Find moment of the force about point O Use Method 2 Find moment of the force about point O Method 3 Use cross product for moment calculations O r F Determine the moment of the 500 N force about point A Determine the moment of the 250 N force about point A Items to complete Submit the classwork ICW 4 6 13 to the submission box on Canvas by midnight Tuesday 6 14 Complete Homework 6 in Pearson by midnight Tuesday 6 14 No FBD s needed Read the MEEN 221 Quiz 3 Instructions with Honorlock before class on Wednesday 6 15 especially File Upload quiz is over 3D particle equilibrium