1. Moments (Lessons 1 and 2)
WALT: Be able to calculate a moment using the equation I must calculate moment from a simple equation I should be able to re-arrange the equation to find force or mass I could apply this to my use of some every-day items

2. In Michaelmas term we learnt about forces…
What is the difference between mass and weight?
In moments, we use weight in N
How do we convert a mass (g or kg) into weight (N)?

3. What happens when you try to open a door with one finger?
Where do you push?
Hi, my name is Mr Stick
hinges

4. Do you push near the hinges?
I can’t do it!

5. Do you push far from the hinges?
That’s easier!

6. The turning effect of a force depends on two things;
The size of the force
Obviously!

7. The turning effect of a force depends on two things;
The distance from the pivot (axis of rotation)
Not quite so obvious!
Axis of rotation

8. Try balancing your marbles
You have 2 minutes
What do you notice about what you have to do in order for it to balance?

9. pivot
Moment
Force

10. Where is the
pivot?

11. 5N Force 3. Which direction will the .What does see-saw turn?
this number
Mean?
2. What is
this?
A pivot
Anti-clockwise
Force

12. How can we increase the size of the moment (the turning effect)?
Pivot
Distance from force to pivot
Force (effort)

13. How are force, distance
and moment related?
moment F d

14. 10cm 5N 50Ncm pivot Calculate the moment (turning effect) of the force
applied to the see-saw. Give the units.

15. 5cm 5N 25Ncm pivot Calculate the moment (turning effect) of the force
applied to the see-saw. Give the units.

16. 10cm
100Ncm
10N
pivot
Calculate the moment (turning effect) of the force
applied to the see-saw. Give the units.

17. 2m
Moment
= 500Nm
pivot
250N
Force

18. 10m 10m 10N 10N pivot The moments of the forces are balanced.
Left
Moment
Right
Moment
100Nm
100Nm
10N
10N
pivot
The moments of the forces are balanced.
The see-saw is BALANCED. But why?

19. 10m 7m 10N 10N pivot The moment of force on the left is bigger
Right
Moment
100Nm
70Nm
10N
10N
pivot
But what happens if the blue dragon moves
in a little?
The moment of force on the left is bigger

20. 10m 10m 20N 10N pivot The see-saw is BALANCED. But why?
Left
Moment
Right
Moment
100Nm
200Nm
20N
10N
pivot
The moment of the force is greater on the right
The see-saw is BALANCED. But why?

21. But can we balance them both again? How?
Left
Moment
Right
Moment
100Nm
100Nm
20N
10N
pivot
But can we balance them both again? How?

22. Now it’s your turn to try!
1) Fill in the TABLE on worksheet 1
2) When you are finished, you can carry out the practicals to complete the second worksheet.
Follow the instructions on your worksheet
Don’t forget to calculate the moments yourself!
3) Once you are finished with all that, can you find the mass of the following items by using your see-saw and masses provided?
-calculator
-notebook
-pencil case

23. Moments and Levers Answer these :- 1. What is the moment of
this force ?
2. What is the moment of
this force?
3. What is the length of this
lever if the moment is
8 Nm ?

24. For each of these, write “balanced” or “unbalanced”.
Balanced both 10Nm
Balanced both 120Nm
Unbalanced: Left is 160Nm, right is 165Nm
Unbalanced: left is 16Nm, right is 15Nm

25. 8m 14Kg 3Kg 60m All of these see-saws are balanced.
Work out the missing number for each one. 8m
14Kg
3Kg
60m

26. 4m
2.5m
640N
400N

27. 4m
10m
200N
500N

28. Moments in Real Life
Pivot
Distance from force to pivot
Force (effort)

29. Think of 5 tools/situations where the laws of moments help us in real life
For 2 of those situations, explain how they work in terms of moments….use language that includes the words “force” and “distance”.

30. Plenary
Write a 5 question “exam” for your neighbour including moment calculations.