What did you learn last time?

1
What did you learn last time?

• 1 thing you learnt from last lesson
• 1 question you had from last lesson that wasnt
  answered
• High 5

2
Principle of moments
26 July 2015

• Objectives
• Be able to define and use the principle of
  moments

3
OUTCOMES

• ALL
• Be able to define the principle of moments
• MOST
• Be able to apply the principle of moments to
  different situations
• SOME
• Be able to apply the principle of moments to
  problems with more than 2 forces

4
Principle of Moments
?

• Total anticlockwise moment

Total clockwise moment

5
Is this Balanced?

• Example 1 (of 3)
• Explain how you know if it is or not (using maths
  to describe)

50 cm
90 cm
x cm
10 N
8 N
6
Practical
7
Example 2 (of 3)
?

• Take moments about the pivot to find the
  distance x.
• (system is obeying
• principle of moments)

8
Example 3 (slightly harder)
?

• Given that the system is balanced take the
  clockwise and anticlockwise moments about the
  pivot to find the force X.

10N 5N 8N
5N
5cm 20cm 60cm 5cm
85cm 10cm
10N XN
Careful, Answer not necessarily a whole number
extension
9
Summary

• Review vid http//www.youtube.com/watch?featurep
  layer_embeddedvWclR1jR0kdk