Albert Teen YOU ARE LEARNING:  Moment of a Force  # Moment of a Force ### Moment of a Force

We will see in this lesson that certain forces may result in rotation of an object, which also has direction.

1

What kind of force is being exerted here? A ________ force.  2

The type of force that is being exerted here is a ________ force.  3

The force that is being exerted on the spanner here is causing the nut to...  4

We call this kind of force "moment"

It's neither a pull force, nor a push force. The force causes the object to rotate. 1

Pull and push forces can operate in different directions

It doesn't matter if you are trying to get your dog to go left or right, you can use a pull force in both directions. 2

Moments can also work in different directions. This image shows a _______________ direction.  3

What is the opposite direction of clockwise?  Pick all the options that describe the use of moments. 1

True or false?

See-saws involve moments, not pulling and pushing forces.  2

A see-saw is rotating around its middle point

Therefore, we talk about moment when it comes to see-saws, not about pushing or pulling forces. 3

This see-saw is rotating in a ______________ direction.  4

What do you think we call point $x$ ?  1

These are PUSHING forces. How big is the resultant force here?  2

What way will the car move?  3

The resultant force is 2 N, acting left

So ultimately, the car will be moving left. 1

How big is the resultant moment here?  2

Which direction will the resultant moment act in?  1

True or false? This see-saw doesn't move.  2

What is the resultant moment here?  3

When the resultant moment is 0 N, the object will not rotate

This see-saw is balanced. 1

To summarise!

Moments are forces that cause objects to rotate around a pivot. 2

An object can rotate in 2 directions

Clockwise or anticlockwise. 3

When two forces oppose each other, the object will move in the direction that the resultant moment is acting in

That means the direction that the greater force is acting in. In this example, that would be in a clockwise direction. 4

If the resultant moment is 0 N, then the object will not rotate

For example, there are 6 N acting on both sides of this see-saw, so the see-saw stays balanced. 