1. MOMENTS Noadswood Science, 2013

2. MOMENTS To be able to calculate moments Wednesday, May 20, 2015

3. MOMENTS Forces can make objects turn if there is a pivot Think of a see-saw – when no-one is on it, the see-saw is level, but when someone sits on the end it tips The see-saw can be balanced again if someone sits on the other end Pivot

4. MOMENTS To work out moments we need to know: - The force (weight) applied The distance from the pivot where the force is applied Moment (Nm) = Force (N) x Distance (m) Pivot

5. MOMENTS Force (F) Moment (M) Distance (D) Force = Moment  DistanceDistance = Moment  ForceMoment = Force x Distance To work out moments we need to know: - The force (weight) applied The distance from the pivot where the force is applied Distance = perpendicular distance, r

6. BALANCED Complete the moments worksheet

7. MOMENTS 600N300N 2m Anticlockwise moment = 600N x 2m = 1200Nm Clockwise moment = 300N x 2m = 600Nm Not balanced – anticlockwise moment Clockwise moment Anticlockwise moment

8. MOMENTS 500N250N 1m2m Anticlockwise moment = 500N x 1m = 500Nm Clockwise moment = 250N x 2m = 500Nm Balanced! Clockwise moment Anticlockwise moment

9. MOMENTS 100N700N 5m3m Anticlockwise moment = 100N x 5m = 500Nm Clockwise moment = 700N x 3m = 2100Nm Not balanced – clockwise moment Clockwise moment Anticlockwise moment

10. MOMENTS 300N450N 3m2.5m Anticlockwise moment = 300N x 3m = 900Nm Clockwise moment = 450N x 2.5m = 1125Nm Not balanced – clockwise moment Clockwise moment Anticlockwise moment

11. BALANCING EXPERIMENT Balance a ruler on a pivot Add a mass at the end of the ruler Your task is to balance the ruler again, by adding 2x masses to the other side Record the distance where they were placed Now move your original mass, and repeat the experiment, recording your results

12. RESULTS ForceDistance from pivot MomentForceDistance from pivot Moment 12 12 12 12 12 Moment (Nm) = Force (N) x Distance (m)

13. CRANES Why don’t construction cranes fall over? Cranes have a concrete counterweight on the short arm, balancing the crane when it lifts a heavy load

14. CRANES Counterweights balance the crane load arm trolley loading platform tower counterweight

15. CRANE OPERATOR

16. M OMENTS Complete the moments higher worksheet… 1. A cross on the point of contact between the screwdriver and the rim of the paint tin (not the end of the screwdriver) 2. Move his hand further from the tin to increase the distance from the pivot, hence increasing the moment, or apply a bigger force (or both) 3. 0.10m x 35N = 3.5Nm

17. M OMENTS 4. (10N x 2m) + (2N x 0.5m) – (35N x 1m) = -14Nm There will be an anti-clockwise acceleration 5. See diagram below…