2. • Know and use the relationship between the moment of a force and its
perpendicular distance from the pivot: moment = force x perpendicular
distance from the pivot
• Know that the weight of a body acts through its center of gravity
• Use the principle of moments for a simple system of parallel forces
acting in one plane
• Understand how the upward forces on a light beam, supported at its
ends, vary with the position of a heavy object placed on the beam
Learning Objectives
5. Moments
• The turning effect of a force is called the moment. Moments are
used to describe the turning effect of a force. Previously, we mentioned
that the turning effect causes the rotation of an object. Now, we can say
that moments cause the rotation of an object.
• Moments vary in size. The size of the moment will affect the amount
of rotation produced. If a moment is bigger, then the object will
experience a lot of rotation. If the moment is small, then the object will
experience very little turning force. In the next section, we will discuss
how to change the size of a moment.
6. When we are calculating the size of a moment, it is very
important to remember that the force is always acting at
right angles to the distance measured