9th igcse-physics-moments of force

1. Effects of Forces-
Moments

2. Learning Outcomes
• To identify what are the forces that will give rise to
clockwise/anticlockwise moments
• To calculate clockwise/anticlockwise momenrs
• To use the Principle of moments to solve numericals

3. What is
Moments?

4. Moments

5. Moments

6. Moments
The moment of force depends on the following
factors:

7. Moments
The moment of force depends on the following
factors:
• The size (magnitude) of the force
• The perpendicular distance between the line of
action of the force and the turning point which
is called the pivot

8. How do we
calculate the
moment of force?

9. Moments
Moment of force= Force x perpendicular distance
from the pivot to line of action of
the force
Moment = F x d

10. Moments
Moment of force= Force x perpendicular distance
from the pivot to line of action of
the force
Moment = F x d
Moment is measured in Newton metres (Nm)

11. What are the
Types of
Moments?

12. Types of Moments

13. Types of Moments

14. What is a clockwise
moment?

15. Clockwise Moment

16. How to determine
clockwise or
anticlockwise moment?

17. Clockwise Moment

18. Clockwise Moment

19. What is a anti-
clockwise moment?

20. Anti-clockwise Moment

21. How to determine
anticlockwise moment?

22. Anti-clockwise Moment

23. Anti-clockwise Moment

24. Learning Outcomes
• To identify what are the forces that will give rise to
clockwise/anticlockwise moments
• To calculate clockwise/anticlockwise moments
• To use the Principle of moments to solve numericals
How confident do you feel?

25. Learning Outcomes
• To identify what are the forces that will give rise to
clockwise/anticlockwise moments
• To calculate clockwise/anticlockwise moments
• To use the Principle of moments to solve numericals
How confident do you feel?

26. Let us Calculate
moments

27. Calculating Moments

28. Calculating Moments

29. Calculating Moments

30. Calculating Moments

31. Calculating Moments

32. Let us look at
some examples

33. Can you find the
force and
distance?

34. Can you find the
force and
distance?

35. Can you find the
force and
distance?

36. Can you find the
force and
distance?

37. Can you find the
force and
distance?

38. Learning Outcomes
• To identify what are the forces that will give rise to
clockwise/anticlockwise moments
• To calculate clockwise/anticlockwise momenrs
• To use the Principle of moments to solve numericals
How confident do you feel?

39. Learning Outcomes
• To identify what are the forces that will give rise to
clockwise/anticlockwise moments
• To calculate clockwise/anticlockwise momenrs
• To use the Principle of moments to solve numericals
How confident do you feel?

40. Let us look at the
Principle of
Moments

41. Principle of moments

42. Principle of moments
clockwise moments = anticlockwise moments

43. Principle of moments
Let us Solve some
numericals on
Principle of Moments

44. Principle of moments

45. Numericals on Principle of moments

46. Numericals on Principle of moments

47. Numericals on Principle of moments

48. Numericals on Principle of moments

49. Numericals on Principle of moments

50. Numericals on Principle of moments

51. Numericals on Principle of moments

52. Numericals on Principle of moments
Some important points to be noted:
1.The unit for force must be in Newton, the unit
for distance must be in metres.
2.The distance must be measured from the
force to the pivot

53. Numericals on Principle of moments
Find F

54. Numericals on Principle of moments
If the system is balanced, the anticlockwise
turning effects of Force F must be equal the
clockwise turning effect

55. Numericals on Principle of moments

56. Numericals on Principle of moments
In order to balance the 5N force acting at 0.5m
from the pivot, we require 10N force acting in the
opposite direction but at 0.25m

57. Unbalanced Forces
Sometimes moments can easily Unbalanced-
even when we don’t want them to!

58. Numericals on Principle of moments

59. Numericals on Principle of moments

60. Numericals on Principle of moments

61. Numericals on Principle of moments

62. Let us now test
your knowledge

69. When more than one force acts in the same direction, their overall
turning effect is just the _______ of their moments

70. When more than one force acts in the same direction, their overall
turning effect is just the sum of their moments

71. When forces act in a different direction, yet still balance, the total
turning effect in each direction will be the same:

72. 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

73. Learning Outcomes
• To identify what are the forces that will give rise to
clockwise/anticlockwise moments
• To calculate clockwise/anticlockwise momenrs
• To use the Principle of moments to solve numericals
How confident do you feel?

74. Learning Outcomes
• To identify what are the forces that will give rise to
clockwise/anticlockwise moments
• To calculate clockwise/anticlockwise momenrs
• To use the Principle of moments to solve numericals
How confident do you feel?

75. Learning Activity

79. 10N 6N