Learning Objectives

-- define and apply the moment of a force and the torque of a couple and give everyday examples

--recall and apply the relationship moment of a force (or torque) = force x perpendicular distance from the pivot to new situations or to solve related problems

-- show an understanding that a couple is a pair of forces which tends to produce rotation only.

-- show an understanding that, when there is no resultant force and no resultant torque, a system is in equilibrium.

-- state the principle of moments for a body in equilibrium

-- apply the principle of moments to new situations or to solve related problems.

-- show understanding that the weight of a body may be taken as acting at a single point known as its centre of gravity

--describe qualitatively the effect of the position of the centre of gravity on the stability of simple objects

In Sec 3, you learned how force affect motion. In this topic on Torque (Moment of a force) , you will learn how force cause turning to take place.


Torque is a measure of how much a force acting on an object causes that object to rotate.

Explore the following websites to learn about Torque.

1. **www.ylearn.co.uk** Access code :- SMTPM6moduleMoments
2. Moments
3. Moments and turning forces
4. Turning effects of forces

Balancing acts

Forces can cause objects to turn. However, there are times we do not want objects to turn; we prefer objects to be stable, but before that we need to understand what it meant by centre of gravity. Watch the following videos to learn about centre of gravity.

Centre of mass

Now, we need to understand the conditions for stability to happen,
Explore the following websites to learn more about stability and static equilibrium.

Toppling over
Stable structures
www.ylearn.co.uk Access Code :- SMTPm6moduleEquilibrium

Visit one of the following websites to explore the how centre of gravity affects the stability of blocks being stacked ontop of one another.

Block Stacker Tutorial
Blocks and Centre of gravity

Are you able to do balancing with your knowledge of centre of gravity and stability? Let us play some games to find out.