1. Forging new generations of engineers

2. Moments

3. A moment of a force is a measure of its tendency to cause a body to rotate about a point or axis. It is the same as torque. A moment (M) is calculated using the formula: Moment = Force * Distance M = F * D Always use the perpendicular distance between the force and the point!

4. Moment = Force * Distance M = F * D What distance would you use here? 2 ft F = 20 lb D = 2 ft Find the moment about point P: M = F * D M = (20 lb) * (2 ft) M = 40 ft-lb

5. Moment = Force * Distance M = F * D Can you visualize the result of the force acting on the beam? The beam has a tendency to rotate clockwise about point P.

6. Moment = Force * Distance M = F * D 2 ft 0.5 ft F = 20 lb D = 0.5 ft Find the moment about point P: M = F * D M = (20 lb) * (0.5 ft) M = 10 ft-lb

7. Moment = Force * Distance M = F * D Can you visualize the result of the force acting on the beam? The beam has a tendency to rotate clockwise about point P.

8. You have seen how a see-saw will balance on its fulcrum if equal weight is applied at both ends. If two people of unequal weight are on the see-saw, it will rotate about its fulcrum to the side with the heavier person. Fulcrum

9. A see-saw can also be balanced by moving the smaller person further from the fulcrum. If a 45-pound child sat on one end 3 ft from the fulcrum, then how far from the fulcrum would a 30-pound child have to sit in order for the see-saw to be balanced? 3 ft 45 lbs 30 lbs x

10. 45 lbs * 3 ft = 30 lbs * x 135 ft-lbs = 30 lbs * x 30 lbs 30 lbs 4.5 ft = x 3 ft 45 lbs 30 lbs x M 1 = M 2 M 1 = M 2

11. Typically it is assumed: A moment with a tendency to rotate counter clockwise (CCW) is considered to be a positive moment. A moment with a tendency to rotate clockwise (CW) is considered to be a negative moment.