1. Moments and Turning Forces

2. The Lifting Challenge  Who is strongest?

3. What affects the turning force?  Hold a rod horizontally and hang a weight on the rod near your hand.  Have your partner move the weight away from your hand, try to keep the rod horizontal.  What happens?  Now try it with a heavier weight. Force distance

4.  How is the turning force or moment affected by the distance from the pivot?  As the perpendicular distance increases the turning force increases  How is the moment affected by the force (effort) exerted?  As the force increases the moment increases What do you think?

5.  How is the moment affected by the distance from the pivot?  As the perpendicular distance doubles the turning force doubles  How is the moment affected by the force (effort) exerted?  As the force doubles the moment doubles  Therefore Moment = Force x perpendicular distance to pivot Can you be more quantitative?

6. Unit for Moment  Determine the unit for the moment of a force. Moment = Force x perpendicular distance to pivot  Newton metre (Nm)

7. Is Moment a vector quantity?  Does the direction matter? Moments can either be clockwise or anticlockwise.  Calculate the moments below. In which direction are they acting? Clockwise or Anticlockwise?

8.  Find the total moment acting on the bar above.  When more than one force acts in the same direction, their overall turning effect is just the sum of their moments. What if there is more than one force acting?

9. Moments Circus  There are six stations.  Using the sheet provided record the effort used on each object and measure the perpendicular distance to the pivot  Finally, calculate the moment.  Do not forget units!!

10. Experiment -Testing the principle of moments  Using the apparatus given investigate the principle of moments.

11. Experiment -Testing the principle of moments  When forces act in a different direction, yet still balance, the total turning effect in each direction will be the same:  sum of clockwise moments = sum of anticlockwise moments  What did you notice about the anticlockwise moment and the clockwise moment?