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

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

Lesson Four Moment by Moment

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

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!

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.

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.

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.

Moment Example Calculate the moment!

Sim LAB – PhET Balancing Act

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?

Plenary: Levers Reverseword