Physics for year 7 to 9 Turning Effect of Forces. Pearson curriculum.

1. The Turning Effects of Forces
FORCES & MOTIONS

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

3. Have you watch THE MIGHTY LEVER video?

4. The Moment of a Force

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

7. In Balance

9. Answer

10. Center of Gravity

12. When an object is not pivoted through its center of gravity
the weight of the object will produce a turning effect

13. Example

14. Forces on A Beam