A moment is the turning effect of a force. For an object to turn, there needs to be a pivot. When calculating a moment, it is important to know:
To calculate a moment the equation is:
Moment = Force × Distance
An example of a moment is when you push a door open. As you push the handle, the door rotates around its hinges. The force you exerted caused the door to rotate around the hinges (which is the pivot). In this case, the moment is created by you pushing the door, and the result of this moment is the door’s rotation around its hinges.
The action of opening a door serves as a practical example of moments, especially when considering how a door is designed. The handle is on the opposite side of the door to the hinges. This is because the moment of a force is related to the size of force and the distance between the pivot and where the force was applied.
It’s also important to note that the greater the distance between the pivot and the point where the force is applied, the less force is required to complete an action. For example (as you can see in the diagram below), if you try to push a door open, close to the hinges, then you will need significantly greater force.
It’s important to remember:
|Physical Quantity||Symbol||Unit||Unit Symbol|
|Moment||M||Newton-metres||N m or N·m|