1. G8 Topic 9 Forces in Action
Pressure and Moments
G8 Topic 9 Forces in Action

2. Lesson Contents Lesson 1 Spreading the load Lesson 2 Under Pressure
Lesson 3 Using Pressure
Lesson 4 Moment by Moment

3. Lesson Four
Moment by Moment

4. Moment by Moment Sunday, 28 April 2019
Identify how and why thing balance
Describe the affect of turning forces
Explain the principle of moments
Analyse moments in calculations
Link to moments in equilibrium

5. Why does this boat and this crane not fall over
Why does this boat and this crane not fall over? What do you think a “moment” is?
Moments!

6. Turning Forces
The forces acting on this crane are balanced, this stops it falling over
The long ‘jib’ acts as a turning force pulling it down
The counterweight acts as the opposite turning force
This holds the crane in equilibrium.

7. Moments This turning force effect is known as a ‘moment’.
The ‘Principle of Moments’ states that:
“the total clockwise moment(s) is equal to the total anticlockwise moment(s)”
The two factors that affect moments are:
The distance from the turning point (‘pivot’ or ‘fulcrum’)
The size of the turning force.

8. Moments are measured in Newton Metres (N.m)
The Moment Equation!
Moments are measured in Newton Metres (N.m)
Put this equation into a triangle! Write the equation with force as the subject. Write the equation with perpendicular distance as the subject.

9. Moment Example
Calculate the moment!

10. Sim LAB – PhET Balancing Act

12. Moments Questions
A mechanic applies a force of 50 N at a distance of 40cm from the pivot on a wheel wrench. What is the size of the moment?
A plumber uses a spanner on a tap. She puts a force of 100 N on the spanner 15 cm from the tap. What is the size of the moment?
A) Calculate the clockwise and anticlockwise moments on this crane
B) If the distance of the left-hand load is reduced to 20m from the tower, what is the maximum load that can be lifted?

13. Plenary: Levers Reverseword