1. Quick Questions
Draw a FBD showing the 2 horizontal forces in a sporting action of your choice (2)
Draw a FBD showing the 2 vertical forces in a sporting action of your choice (2)
Describe Newton’s 3 Laws of motion (3)

2. Biomechanical Principles – Centre of Mass and Stability
Biomechanics
Biomechanical Principles – Centre of Mass and Stability

3. Learning Objectives Learning Objective:
Understand how centre of mass can affect stability.
Learning Outcomes:
All: Describe the relationship between Centre of Mass and stability
Most: Apply your knowledge of centre of mass an stability to a variety of sporting examples
Some: Explain how athletes can use their knowledge to maximise performance

4. Key Terms
stability = the ability of a body to return to equilibrium after being displaced.
centre of mass = the point at which the body is balanced in all directions.
equilibrium = a body is in equilibrium when the net force is 0 - all forces are equally balanced

5. Balance and Stability – how does it affect performance
(5min video)

6. factors affecting stability
low centre of mass the lower the centre of mass, the higher the stability
increase size of base of support the larger the base of support, the higher the stability
line of gravity is central to base of support if the line of gravity is central to the base of support, stability is increased
increased body mass or inertia a performer with a larger inertia/mass will have a greater stability

7. Lets have a go
Take part in the following activities to see who can increase their balance and stability
1 v 1 – who can push the other across from room
Headstand / handstand
Stork stand / dancers pose

8. Would these athletes want to increase or decrease their stability? Why?
Rugby player in a scrum
Diver
Sumo wrestler
Sprinter out of the blocks
High jumper
Gymnast

9. Exam Questions
June b) Using examples, from sport, explain how performers maximise their stability. Using examples from sport, describe why a performer might want to minimise stability in sport. (5)
June a) What is meant by the terms ‘line of gravity’ and ‘base of support’? Use practical examples to show how a performer can maximise their stability. (4)
Jan b) What is meant by the term centre of mass and how does this help to explain why the Fosbury Flop is the preferred technique for high jump? (4)