2. AQUINAS DIOCESAN GRAMMAR Moments Double Award - Physics 3.5.23calculate the moment of a force as force times perpendicular distance form the pivot. 3.5.24describe some practical applications of levers. 3.5.25state the principle of moments and use it to solve simple problems. Calculations limited to two forces other than that acting at the pivot. Perpendicular distances only will be given.

3. AQUINAS DIOCESAN GRAMMAR Moment of a Force The turning effect or moment of a force depends on The size of the force How far it is applied from the pivot or fulcrum

4. AQUINAS DIOCESAN GRAMMAR Moment of a force = force x M = Fd Perpendicular distance from the pivot (fulcrum) The unit is the newton metre (Nm)

5. AQUINAS DIOCESAN GRAMMAR In the illustration below a force F acts on a gate in (a) at the edge, in (b) at the centre. Hinge (fulcrum) O F = 5N 3 m O F = 5N 1.5 m (a) Moment of F about O = 5 N x 3 m = 15 Nm (b) Moment of F about O = 5 N x 1.5 m = 7.5 Nm

6. AQUINAS DIOCESAN GRAMMAR The turning effect of F is greater in (a); this agrees with the fact that a gate opens most easily when it is pushed or pulled at the edge.

7. AQUINAS DIOCESAN GRAMMAR Moments about a door Moments Quiz Quiz 1 Quiz 2 Quiz 3 Quiz 4 Quiz 5

8. AQUINAS DIOCESAN GRAMMAR Practical Applications of Levers

9. AQUINAS DIOCESAN GRAMMAR More examples of levers

10. AQUINAS DIOCESAN GRAMMAR More examples of levers

11. AQUINAS DIOCESAN GRAMMAR Levers in the human body

12. AQUINAS DIOCESAN GRAMMAR Principle of Moments (also called the law of moments and law of the lever) When a body is in equilibrium the sum of the clockwise moments about any point equals the sum of the anticlockwise moments about the same point

13. AQUINAS DIOCESAN GRAMMAR For equilibrium Sum of anticlockwise moments = Sum of the clockwise moments Taking moments about A F 1 d 1 = F 2 d 2 F1F1 F2F2 A d1d1 d2d2